If you are refusing to pay then they will persue the debt using any avenue open to them up to and including putting a charge on your house.
It should not come to this however as they will probably fist seek a ccj but if you have equity then they can apply for a charge to be put on your house, they can't force you to sell but they can put themselves in the queue when you sell it. Can you supply more info, ie are you just refusing to pay? are you disputing the ebt in some way? what are the curcumstances?