Trying to remortgage after bankruptcy

My husband went bankrupt before we met. He's been discharged for 7 years. We want to borrow against the house to build an extension. It was all approved until it came to light that there is a charge against the house.
When he went bankrupt his parents bought the interest in the house to stop a charge going on the house so we don't know why it is there. Unfortunately, the company that handled his bankruptcy has closed so he can't get them to remove it or get any proof that it shouldn't be there. He's being passed all round the houses trying to get it sorted. Has anyone dealt with this sort of thing before? I would really appreciate advice on how to resolve the issue as we're just going round in circles here!