Can they actually do this to me? Do I have any rights?

hi guys, hope fully some one can advise me. i had my house repossessed 4 years ago, my friend and i brought the property part ownership for £118 k so we had a mortage for 57k(with halifax). we couldnt keep up payments so the house was repossessed after 3 years. it was up for sale for £138k before it was repossessed but the buyer pulled out at the last minute. i thought as it was repossessed that was the end of the matter. halifax's solicitors are now chasing me for £24,500 as they are saying that s they only managed to get £98,000 for the property at auction. 2 things that sound fishy to me about this is...we were to sell the property for £40,000 more only 6 months before they sold it, so they have dropped the price a lot to recoup some money. also we only borrowed £57,000 so if the house was sold at £98,000 and we are only eligible for the 50% ownership of this, surely we should only be owing £8000 there abouts?? please advise thanks x x

hi guys, hope fully some one can advise me. i had my house repossessed 4 years ago, my friend and i brought the property part ownership for £118 k so we had a mortage for 57k(with halifax). we couldnt keep up payments so the house was repossessed after 3 years. it was up for sale for £138k before it was repossessed but the buyer pulled out at the last minute. i thought as it was repossessed that was the end of the matter. halifax's solicitors are now chasing me for £24,500 as they are saying that s they only managed to get £98,000 for the property at auction. 2 things that sound fishy to me about this is...we were to sell the property for £40,000 more only 6 months before they sold it, so they have dropped the price a lot to recoup some money. also we only borrowed £57,000 so if the house was sold at £98,000 and we are only eligible for the 50% ownership of this, surely we should only be owing £8000 there abouts?? please advise thanks x x