Product: Credit card

We routinely, electronically paid our monthly credit card bill in mid XXXX through our personal bank. We were notified about 2 weeks later by the credit card company that we had failed to pay our monthly bill and should we not pay the bill there would be late charges, adverse credit report actions, etc. We immediately sent another electronic check to pay the bill and contacted our bank to investigate this. Over the course of the next 2 weeks we identified that what happened is that the original electronic check went through to the credit card company and they coded it incorrectly and so could n't cash the electronic check. The XXXX check we sent went through fine and subsequently the original electronic check was also cashed on our account. So we paid the credit card company XXXX. In working with both our personal bank and the credit card company over the past 7 weeks we have now been credited for the original check and the XXXX check EXCEPT that the credit card company continues to say they only cashed {$1800.00} of the {$2000.00} of the original check and they refuse to credit us the remaining {$200.00}. The following events have occurred : -originally the credit card company stated they never received the original check and blamed our bank-after our bank investigated it was found that the credit card company had been at fault by miscoding the original check. The credit card company acknowledged this. At this point the credit card company told us they only received {$200.00} from the original check not the $ XXXX-after further discussions with our bank and the credit card company, the credit card company then said that they in fact got {$1800.00} of the original {$2000.00} but that we had issued a stop payment of {$200.00} on the original {$2000.00} check. This stop payment allegation never happened. 
-At this point I had a representative from my banks executive team speak with the credit card company personally and told them 1 ) no stop payment had ever been issued on the check in question, 2 ) it was impossible to issue a partial stop payment on a check ( i.e. we could n't have stopped payment on only {$200.00} of a {$2000.00} check ) and 3 ) all our bank 's records showed that the credit card company had in fact cashed the full {$2000.00} of the original check. We even submitted a copy of the original check to the credit card company which showed it had been deposited. We should have then been credited the remaining {$200.00} on our account. 
-We just received another letter from the credit card company still stating that they now want our bank statements for the past 2 months to investigate this further. We still have not had the {$200.00} in question credited to our account. 
This has been an ongoing problem for the past 2 months now. We have been repeatedly given different accounts from the credit card company over what they say happened. I have had our personal bank executives contact and speak with the credit card people to tell them what happened and that what they are alleging could not have happened and that the credit card company has made several errors it appears throughout this. It is an unreasonable expectation from the credit card company to ask for two months of personal bank statements. We have tried to work with them and our bank has even spoken to them. We would expect that this {$200.00} be credited to our account immediately as all of our banks records show that this check in question has been cashed weeks ago. 
Of note, XXXX from the XXXX Executive Team ( phone XXXX ) helped with this and our Citibank contact has been XXXX, ID # XXXX ( phone XXXX ).