mortgage shortfall advice needed please

my partner took out a northern rock together mortgage, some years before we got together. She didnt really understand exactly what she was agreeing to, but it turns out a large element of the mortgage was interest only, and also an interest only loan element.
3 years ago we decided to move in together and she rented her property out, but the rental income didnt cover the mortgage payment each month. At the end of last year the tenant gave notice and my partner decided she'd put the house on the market. Its been 6 months now and theres been no positive interest in the property or any firm offers until the other day. Cash buyer, offered £7000 under asking price (£130000).
Shes called NRAM today to find out what her current debt is, and been told the mortgage element is around what the offer is (give or take) but the interest only loan element takes the debt upto £144000.
She can take the loan element and carry on paying but has no way of eventually paying it off, and NRAM will increase the already ridiculous percentage rate.
I believe she was missold the mortgage, and she put a complaint into NRAM last year, but was told they didnt missell and the case was closed.
Her credit rating is now so bad, she cant get a cheaper loan to pay off NRAM, so shes stuck.


Can anyone give sound advice here please.