My question involves a consumer law issue in the State of: Texas

My Sister and I went to a "reputable" luxury car dealership couple months ago to get her a car. Since I was a prior customer there, I thought it would be a good idea to take my sister there. I went with her for the purpose of negotiating a better term for her lease. After terms were set I left the dealership because I had prior obligations. Before I left I stated I did not want to be a cosigner for the vehicle. After I left she signed the paperwork and all was well... so I thought. The following month she did not receive a bill from the financial service company. After making the call to them they told us that there were no accounts under her name, so we called the dealership and they gave us the excuse stating that the application got kicked back but there were no problems. We made callsmultiplee times to both the dealership and financial organization for the bill and finally they sent the first bill 2 months later with late charge. After talking with the financial service multiple times we had to pay thelump-summ and they waived the late fee.

Problem insued when I applied for a car loan and was turned down for having excessive borrowing... after checking my credit report, I found that the dealership that my sister bought from put me down as a co-signer. After talking with my sister who showed me her lease contract I realized that my name and signiture was no where on it. I called the financial services company to sent me their copy of the same lease contract. I receive the contract from them with my signiture which was obviously forged!!!! I am very upset! Can anyone tell me what to do? Is there any punitive damage I can collect? What will happen to my sister's contract, isn't that contract void? Since this should be criminal act should I goto the DA's office first or to a lawyer first? Please help!