muskey.
From your post it is a case of {could never have afforded} and your loan @1.8 = your debt @1.8.
..............................................
The sensible approach,( not what you want), is to sell @1.8 and get on with life.
Havbell will probably live with interest only until they get round to you , but I just cannot see them leaving interest only long-term, particularly if you are on a low rate.
For now can I suggest .
1. Keep paying the interest element.
2. Review your finances and see what capital repayment you can manage medium term.
3. Await Havbell coming to you and give them your realistic proposal.
4. If the figures do not add up , sell up , as you probably do not want this dragging on and on.