Product: Credit card or prepaid card

This Complaint is against Comenity Bank of XXXX, Ohio for not crediting our XXXX credit card account which card is owned by Comenity Bank with an electronic payment made in XX/XX/XXXX. They deny that the payment was made despite our submission of all data and documents to prove that we made the payment and was received by Comenity Bank. We have previously submitted all relevant information to prove our position to Comenity Bank but never received any official response except as noted below. 
In XXXX, XXXX, we made various purchases from XXXX totaling {$610.00} which were billed to us on a monthly statement in XXXX, XXXX. The XXXX statement was paid on XX/XX/XXXX by electronic funds transfer from our local bank checking account consistent with the same method we had used to pay similar statements more more than the prior twelve ( 12 ) months without any problems. 
When the XXXX, XXXX credit card statement arrived, we noticed that the XXXX payment had not been posted to the account and telephoned Comenity to have them correct their error. In response, they sent us a " form '' letter requesting documentation to support our claim rather than undertaking any review of their records. 
We mailed them documents which showed that the funds were removed from our checking account on XX/XX/XXXX and electronic funds routing records showing that those funds were transferred to Commenity with proper instructions to credit our card account, including the proper credit card account numbers. No funds were ever returned to our checking account. 
We were then told that perhaps we had erroneously inserted the credit card account numbers and to check our credit card statement against the electronic funds transfer instruction and requesting that we send them any documentation to support our claim. We did this, confirmed to them that the account numbers were identical and sent all of our documentation a second time ( incidently, our electronic payment instructions were preprogrammed into our bank 's system and had worked automatically without error monthly for more than a year ). This resulted in a letter to us dated XX/XX/XXXX stating that they would research the matter and stating that 90 days may be required to respond to us. 
Subsequently, we received a refund check from Comenity for {$610.00} which we did not cash. It became void by the passage of time, and we returned it to them. This action was followed by a third letter dated XX/XX/XXXX, requesting 90 days to further review the matter. We heard nothing further from Comenity. 
In early XXXX, we began receiving collection calls from Comenity saying that we were delinquent in credit card payments since XXXX, XXXX and demanding immediate payment of the original amount plus interest and late payment fees. We repeatedly told callers that we had a dispute pending and did not owe the money. The only response was that the caller would so note on our file. 
Finally, about XX/XX/XXXX, a collection caller referred our call to a manager who said that our complaint had been reviewed, found to be without merit and the file closed. Hence, collection was now being pursued. If we had any continuing issue, we should should pursue our bank or the electronic funds transfer provider. She said that her screen did not provide any information about the dispute or the reasons Comenity made its decision. 
None of this had been communicated to us by Comenity and no one had ever provided any statement of evidence to support their position or refute our data. 
To us, it appears that Comenity never undertook any investigation of its internal electronic records or of the substantiation we provided. Nothing substantive was communicated to us. We received only the " form '' letter responses.