Synchrony Financial Credit Card Complaint

Synchrony Financial Credit card department,

APR or interest rate North Carolina

I had a verbal agreement with -/Synchrony Bank to close the account and pay $50.00 a month for 48 months ( interest free ) to clear the account. They never told me or send me any written agreement of the condition of the arrangement. After making few months payment I somehow missed a payment and they immediately cancel the arrangement without notifying me and started charging interest and late payments fee and cause a past due balance of $290.00 which I made for - -.