Synchrony Bank review: Mohawk and care credit cards

I purchased new flooring and was approved for a Mohawk credit card. At the time of purchase I was unaware of any promotions. I called Mohawk customer service on 5/11/23 and spoke with Jonathan, who told me the promo had ended and $1900.00 interest was charged to my account. The same thing happened on my Care Credit account. I was unaware of any promotions at the time of purchase. I asked to speak a supervisor to dispute the charges and the phone call was disconnected. I called back and the female representative placed me on hold for several minutes and the call disconnected. I wrote a letter in regards to this issue some time in June 2023. I never received a response. I continued to pay both accounts. I have 4 active accounts with Synchrony Bank, which are all paid on time. I called again on 11/9/23 and spoke with Jade. She states a letter was sent to me but she could not verify my address of where the letter went to and the Mohawk account has been closed. I again asked for a Supervisor and was disconnected. My next option is to file a complaint with the Better Business Bureau or take legal actions. Please reply as this is an urgent matter.