tbh your settlement figure probably wont be far off the apporx �8700 ish you owe now. Companies make their money by tying you into a repayment schedule, and usually use the payments made to pay off the interest first. if you pay it off early, there is no profit in it for them therefore they probably wont reduce it all that much
as ethel say, the only way to find out is to ask them, but i cant imagine they are going to be happy, when they thought they were gonna get regular money off you for the next 4 1/2 years, and now they wont. In any case, the charge for finance will still be payable