Whilst any excess money goes to the homeowner, they are also liable in the event of a shortfall. They can and will be chased singly and/ or jointly for 12 years for repayment. The reposession/shortfall process allows attachment of earnings and charges on any future dwellings they may own, subject to additional court proceedings and associated costs.
It is also of interest to note that until the date of exchange of contracts with new buyer, the repossessed homeowner may pay the arrears and mortgage interest to date and reclaim their home or secure their own sale (subject to covering lenders total debt).
The lender will charge for everything, an average reposession costs £7k-£8k
If vendors property is to be sold at auction, they can bid for it and buy it back (subject to funds being available), they can even buy their home back through the lenders
EA subject to a mortgage being in place etc.
Never give up on rescuing repossessed houses if they had 20% equity or more.