I recently had a kitchen installed, after two weeks the work surface started to discolour, the store I bought it from acknowledged the problem and promised to replace it and they also promised to pay for the refit providing I produced an invoice; the work was done and they were given the invoice, they now say the cost of refitting is not their responsibility and offered me ten percent of the refit cost as a good will gesture!? I now have the fitters bill to pay? what are my legal rights and how do I enforce them so this invoice is paid?