Complaint sub-issue: Problem during payment process

I have a Citi XXXX Visa. I made my payment through my online banking with XXXX XXXX. XXXX XXXX debited my account in the amount of the payment - {$6700.00} on XX/XX/XXXX. Payment due date was XX/XX/XXXX. XXXX XXXX used a check to pay the bill, rather than paying electronically. I use this online banking for all bills that I can. They can do some payments electronically, but not for Citi. 

In many years of using XXXX online banking, I've had only one other late payment issue regarding a credit card. In that case, it appears to have been late because of slow processing by the credit card company and a long weekend during the interim. I have started the process with XXXX by filing an online banking claim. 

Perhaps relevant is the fact that my husband has a Citi XXXX Visa card of his own - different account numbers. We do our online bill pay together from a joint bank account. His payment due date was XX/XX/XXXX. The payment from XXXX to his Citi card was made through online banking on XX/XX/XXXX. 

We checked both accounts online on XX/XX/XXXX. Neither payment had posted to the accounts as shown in the online access for those accounts. We initiated a chat on that day for my husband 's account and asked about the fact that the payment ( {$70.00} ) had not posted. The agent on the chat indicated that she showed the payment had been received on XX/XX/XXXX. It did not show, however, in the online access of his Citi card until we checked the account on XX/XX/XXXX. 

I checked my Citi account on XX/XX/XXXX and it still did not show as having been received by Citi. We did a chat with them and called them and XXXX XXXX to figure out what was going on, since at this point Citi showed me as having missed my payment and had assessed a late payment fee of {$100.00}. XXXX said that they showed the payment coming out of our account, but didn't have record of the check having been cashed by Citi. When I called Citi, I asked them to do an investigation, but they said their system looked like it would require a cashed check to actually investigate.

Aside from helping to expedite the resolution of the issue, I have two complaints for the CFPB. First, in both of the online chats that we did for my husband 's card and mine, the agents both made a point to encourage us to use their system to make online payments, because the payments would be posted the same day. It seemed to me that it was not a coincidence that the agents both suggested that. Considering the fact that the online access didn't show the payment posted to my husband 's card until 3 days after Citi received the payment, I'd like to hear from Citi about how this process works to reassure me that they aren't using this time lag to my detriment.

Second, I'd like Citi to explain the payment investigation process. When I talked with the agent, she didn't seem to contemplate how the investigation would work for a paper check mailed to Citi. They seemed to require a canceled check to initiate that investigation and made me think that an investigation would not even be started because they didn't have the check. It occurs to me that a paper check from me or from a bank via online banking has to be handled and processed. There was clearly a lag for the check on my husband 's account from receipt to posting. What's the investigation process for finding a check in your system?