Synchrony Bank Credit Card Complaint

Synchrony Bank Credit card department,

Billing disputes Georgia

- -, 2015 I have had misunderstandings with Lowe 's /Synchrony Bank for the last 8 months. I have paid my account out in full but they have added interest to the account. - gave me 6 months to payoff the account but the bank did not honor this. They begun to add interest from the beginning. I have paid my account in full but they have added the interest which almost doubles what I have paid them. I opened the acct. in -/-/-, paid this one out and charged a microwave in -/-/- and paid it out in - 2015. Please help me with this account and retain my good credit. I am too old for problems now. Thank You.