Exhaustion of funds erroneously.

My mother has visited the Dr two times this year and ended up being hospitalised. After being discharged from hospital she received a statement saying her day to day funds have been exhausted. She called to find out how is it possible as she has only visited the Dr twice and was told that they made a mistake by paying for some of the hospital bills using her day to day funds and that it would be corrected. It has been over a month now and they still have not corrected the mistake instead, they keep giving excuses. This is worrying because she is on chronic medication and needs to visit the Dr regularly and can't do so due to lack of funds.