Product: Checking or savings account

My wife and i had a joint checking account with HSBC US and separate HSBC US XXXX facilities up until early XXXX XXXX. Through their customer Outreach Dept a decision was taken to close our checking account and terminate our HSBC XXXX accounts. 
The only reason we can think of for this action to be taken was that we were unable to answer a series of questions about our personal financial circumstances within a given timeframe. 
Both my wife and myself think their action was extremely unfair since we did manage to communicate at least on one occasion via the telephone and having not undergone this process previously we had no idea of the seriousness of the situation. The other major contributing factors that we believe could have led to this decision was the fact we live overseas, and it would appear HSBC Outreach Dept. 's lack of awareness with regards to our situation. 

Here is some background to our case. 
As mentioned above we had a joint checking account and HSBC XXXX. These were opened around XXXX and we have had no major problems prior to this. Our living overseas is down to working for the Federal Government XXXX XXXX specifically XXXX. This was advised to HSBC back in XXXX where our first posting was to XXXX. In XXXX we were posted to XXXX and again HSBC was made aware of this prior to our arrival. We had also clearly indicated on their online banking website that our preferred mode of communication was EMAIL. This point is very important since the telephone services were both unreliable and often poor quality. Sending urgent documents via regular mail was also problematic since all post to us comes through a Diplomatic Pouch which can take up to 4 weeks. 
We finally became aware that there was some urgency in this matter when we were away on leave to XXXX and XXXX. We left XXXX on the XXXX XXXX XXXX and did n't arrive back home until the XXXX XXXX XXXX. Whilst away we contacted HSBC about another matter and during that conversation we were asked if we could speak to someone ( I believe from the Outreach Team ) regarding certain information they required to complete their records. I personally spoke to someone answering various questions about my financial situation but for some reason they never asked to speak to my wife. At the end of the call I was left with the impression that they had as much detail as they needed but would get back to me if more questions arose. During this conversation there was no discussion about whether we had received earlier communications requesting information and the urgency behind any subsequent request that might be forthcoming. 
Upon our return to XXXX, my wife went back to work on XXXX XXXX and collected from the US Embassy the post that had accumulated whilst away. We received three letters from HSBC dated XXXX XXXX, XXXX XXXX and XXXX XXXX. One was addressed to my wife, another to myself and one to the both of us. Even the earliest did n't reach us in time before we left XXXX. 
We also noted that in one of the communications dated the XXXX XXXX it stated that we had 'recently relocated to XXXX XXXX. We simply do not understand where this line of thinking originated. Our records should have clearly indicated that we were posted here 3 years ago! As mentioned above we certainly notified HSBC of this situation and we have had numerous transactions originating in XXXX. The communication also went on to ask for various personal documents related to net worth, income etc and requested we send copies via pdf. At this time as mentioned above we were in XXXX and XXXX so we had no way to retrieve the information they requested by the date required. If their request had been sent by email it could have been flagged immediately - we would not have been able to provide the information at that time but we could have entered into a discussion about a timeframe that would work for all concerned. 
During that first week back from our leave I also contacted the Outreach Dept on a number supplied to speak to the individual identified in the letters. I made sure i called during US office hours but only ever managed his/her answerphone. I left a number of messages explaining our situation and that i 'd be happy to answer whatever questions he/she had to the best of my ability. I also informed him/her that I would call them at a time that suited their schedule and supplied my email address which they already had on file as a reminder. At this time at the beginning the account was still open and there were no messages from their online banking website advising they were about to close the account. I did use the bank mail as a further option to let them know we 'd been away for a lengthy period and were now back ready to assist with their enquiries. I got confirmation that this had been passed on but no communication was received from the Outreach Dept ( which considering their name seemed a little strange ) to arrange a possible appointment to discuss. 

Where are we now? 
Well it has caused us a great amount of disruption to our daily lives. Living where we do the day to day stuff that might be taken for granted becomes super important. Reliable and secure banking facilities are a key element in maintaining a standard of living we would expect back home in the USA. In addition we have also missed credit card payments which we have never done before. Money was transferred into the checking account to cover a due payment. Unfortunately with the timing of the account closure and without any final urgent warning we could not action the appropriate transfer and now the balance has been sent to us via a cheque in the mail which will likely take weeks to get to us. 
Finally we had also accrued thousands of reward points on our credit cards which are worth many hundreds of dollars. These have now just 'gone ' as our XXXX facilities were terminated. 
The most frustrating thing about this whole unfortunate affair is that we still do n't know why our account was closed. Had we failed some internal vetting procedure or simply missed a deadline? 
We still just want our banking arrangements restored. That 's all we 're asking for. 
I 've been in touch with a banking official at the branch where we opened the account but they are yet to come back to me with any answers or suggestions. 
Due to where we live it 's not possible to meet face to face with someone to discuss so we 've had to rely on skype and email. So far we feel we 've hit a brickwall - have we been treated unfairly and do we have any grounds for at least a hearing? 
We 'd like to think so. 
Any advice or help you can give would be very much appreciated. 
B Regards XXXX & XXXX