I am not entirely surprised they are refusing to hand over the MIG because the BS stance has always been that whilst you paid for the MIG, the BS was the beneficiary, not you - I believe there is case law that supports this.(posted 7250 days ago)Mortgage deeds vary in terms of style, number of sheets etc. Some may only be one page and then refer to "General Conditions" which are on a separate sheet, fold, or batch of papers.
When you were repossessed - if this was done by a possession order rather than you voluntarily moving out, the judge, at the time, would have asked to see the mortgage deed to ensure it was in order - if it was not, then a PO could not be granted.