My son bought a flat in joint names with his wife 10 years ago. They divorced soon afterwards, but her name was never removed from the mortgage even though she wrote a letter to the bank to say she wanted nothing more to do with the flat. This letter has now been lost, and the building society says my son needs his ex-wife’s permission to sell, even though he’s been paying the mortgage all these years. He doesn’t even know where she is.
It would appear that the bank wasn’t prepared to release the ex-wife from her responsibility towards the mortgage, so a court order would have been required to transfer the property into your son’s sole name or the house should have been sold. If your son instructed a solicitor to handle his divorce he may have a claim for compensation.