Synchrony Financial Debt Collection Complaint

Synchrony Financial Debt collection department,

Credit card Cont'd attempts collect debt not owed Debt is not mine Nevada

I did hold a credit card account with - issued by Synchrony Bank from -/-/- till -/-/- when it was closed. On -/-/- was the last payment made on the card showing zero balance. Since -/-/- till -/-/- there was no activity on the account. During the months of -/-/- I have received a notice from a collection agency that I owe them $690.00 that they claim I did not pay -. When asked to prove the charges no one was able to produce said charges because they never existed. Since -/-/- till now I have not received what I have requested but said information was reported to the credit bureau as bad debt. Merchandise was returned to - and credit was received but Synchrony Bank or - some how decided that I owe them the $690.00 when that amount was credited to the account based on merchandise returned to them.