Discharged debt on deceased husband

My husband passed away last year, we had a loan on a vehicle, I sent in an application to assume the loan, it got approved and In October, I signed and got notarized all neccessary paperwork and mailed it in. I was told I had to be current with no late fees to get loan complete, I cont. making the pmts to bring current, In Jan I brought the loan current and never received anything in the mail about the loan being changed, I continued making payments under my husbands name. In June when I called the automative pmt line, It said my balance was 0. I called someone the next morning asking why I couldn't make a pmt. She stated the debt had been charged off because the assumption paperwork was never received. In Oct they had them but now in June they say they never rec'd them and that is why the loan was never assumed, so they discharged it. I am still making pmts to them but have to mail them in. They state that I need to continue with pmts to them and when it is pd off they will release the title and then I will have to figure out how to re-title it in my name. What are my options and can they still take the vehicle if these pmts are not made. I have gotten nothing in the mail about this discharged debt or any recp't of pmts made after other than my cancelled checks.