Hello and thank you for contacting us. This is Dwayne B. and I’m an expert here and looking forward to assisting you today. If at any point any of my answers aren’t clear please don’t hesitate to ask for clarification. Also, I can only answer the questions you specifically ask and based on the facts that you give so please be sure that you ask the questions you want to ask and provide all necessary facts. Further, if you get a message asking if you want to do additional services like a telephone call that message is automatically generated by the website and is not sent from me. I, like most of the experts in the Legal categories, do not do telephone calls due to issues with State Bar rules and other concerns.
The main issue in your case is going to be regarding the written agreements since it is nearly impossible to prove any oral statements or agreements. It is by no means impossible to sue based on oral agreements or contracts, it's just extremely hard to do so.
Your potential liability depends on the agreements. Most credit card agreements state that 0% only applies for a short initial term, a few months to a year or two although, certainly, there could be ones for longer. If you signed or otherwise acknowledged an agreement to a future interest rate then you would be responsible for whatever that rate is. In addition, many of those agreement offering 0% allowed that interest rate for a year but if the transferred amounts were not paid off within a year then the interest rate was back dated and charged on any unpaid amounts for the entire duration since the transfer.
As to options, you can report them to the Fair Trade Commission at www.ftc.gov and to your state's attorney general but those methods usually don't get a lot of results, unfortunately.
The only real option you have is to hire a lawyer and pursue a lawsuit against them for the various causes of action including breach of contract and, potentially, fraud. You can locate a lawyer to assist you at www.lawyers.com and in the box for Area of Practice enter Consumer Law.
In a successful lawsuit you can be awarded any amounts you paid above the rate you were promised, have them ordered to correct any erroneous information reported to the credit agencies, recover any additional damages you can prove, and recover attorney's fees and costs.
Please ask any follow up questions in this thread.