Removing Name From Mortgage & Deeds

pipps0316

My uncle and grandmother purchased a house from the council 9 years ago. 3 years into the purchase my uncle left unannounced, leaveing my grandmother to keep up the re-payments, which she has done without fail. During the last 6 years, my grandmother was informed that my unclue had a breakdown and was sectioned under the mental health act. Bringing a long story to an end, we have documentation from each NHS hospital he was remanded in, documentation from the police where he was reported missing from hospitals etc, yet my grandmothers mortgage lender will not remove his name from the mortgage. He has left many debts at the house, though answer all demands with the relevent information. Can anybody advise where best to seek advice or what steps we must take to remove his name from the mortgage and deeds? The remaining mortgage on the property is less then £20k, unsure if that makes a difference.
Thanks Pipps