Advertising and marketing, including promotional offers: Credit card

I financed $1800.00 through Synchrony Bank and was told I had 12 months at 0 % interest. I was not informed that if the balance was not paid in full within 12 months, interest would be charged retroactively from the purchase date. After making payments for nearly two years, I discovered substantial interest had been added. I am requesting a review of my account and the promotional financing disclosures. I still own them $1700.00 so the payment I was making all this time did not add to my account, Im asking for my payment back or for the interest to be removed.