Negative equity Lump sum offer.

Chimpolito

How it worked with me was that if you do not have the funds to pay the shortfall or ability to borrow it, tell the lender who will decide on whether to let you sell based upon their valuation of your property. They contacted my estate agents looking at time spent on the market, previous offers etc. Have a word with the agent to make sure they reply favourably to you to the bank's questionnaire. I'm sure it would help if your reason for selling is valid- moving away for work etc.
For me it was a two stage process. Firstly determining whether it was a good sale price for the bank. Then they let me sell it. After the sale came the issue of dealing with the shortfall- which took several months before they chased me. But bear in mind I was offered 0% on repaying the full shortfall over an affordability based time frame- so it may be better for you to investigate this path before taking on any expensive borrowing. It was only when this was being organised that they suggested the lump sum.