Bad service

Hi I have been trying to get to finchoice but with no success as they need my old information which I have been giving to them is like I am getting nowhere as my calls are dropped after they say the information is wrong but what I am asking is that then there is no other solution like send your id copy so that they can verify is they speaking to the correct person. There must be another forms because my account is very old account I can't remember some of the details so my world have to stop due to that. I need a paid up letter from them so that I can sort out credit status.