Product: Bank account or service

This concerns Citibank and their response to fraudulent charges made to our account on a debit card. We saw charges to XXXX that we did not authorize, called Citibank immediately, and the charges were appropriately removed. About two weeks later, we saw those charges re-appear on our account, with an additional new charge, and no description whatsoever. When we contacted Citibank, after over two hours of conversation with various staff and being forwarded multiple times, we were told that the dispute had been refused. We had been given no notice of the refusal, no notice that the charges were again being placed against our account, and no information on what information XXXX had provided to assure Citibank that we had indeed authorized the charges. On the phone, Citibank was completely unable to provide us with any information as to why the dispute had been resolved in the way it had, as to why they now believed the charges to have been unauthorized, and admitted that they had sent us no notification as to the resolution of the dispute, as to the re-charging of the funds to our account, nor any opportunity to respond to the findings. We did not in any way authorize these charges to XXXX, Citibank did not follow proper notification to us, and XXXX ( group number XXXX ) stated that they could not credit the funds back to us pending our request that the decision be appealed. So, we were the victims of debit card fraud, the fraud was found to not be authenticated for reasons that are completely unknown to us, we were not given any notification of this decision, and charges ( including a new charge that we had never seen before ) re-appeared on our bank account with no description or warning whatsoever. Fortunately, we had enough funds in our account to not overdraw any bills, but that could have easily happened otherwise. Upon calling Citibank, they were unable to justify their decision, provide any explanation whatsoever, nor could they refer us to someone who could provide information. They acknowledged we received no notification, and that we were entitled to an explanation but that they could not provide one. As far as we are concerned, Citibank ( and XXXX ) now have financially benefitted from fraud perpetuated in our name and we are being charged for something we did not authorize, did not purchase in any way, and we have been given no reason why this is the case or any information we can use to challenge the decision made by Citibank based on some kind of fraudulent information provided by XXXX. 
We have no idea how to pursue this matter further and feel we should not have to pay for something we did not authorize and should, at the least, have been provided notification and information regarding how Citibank came to this decision and an opportunity to address it. We have filed for an appeal, but Citibank refuses to remove the charges from our account and we are told the appeal process could take many months. In the meantime, they ( and XXXX who we will never use in the future ) have our money without our intent or authorization. 
We 've had many problems with Citibank, especially their fraud division, but this was by far the worst.