No service delivery

I bought a Grandiose kitchen unit at Bears Mayfield with credit and they added all the insurances including the damages of the goods but now my kitchen unit its damaged due to their negligent but they don't come out to fix it since I reported the matter last year December. Then December 31st I bought the last piece of the unit cash when it was delivered it was not complete I reported the matter again but till today no one was sent out to fix but every month I pay my full instalment that is not fair on me. Please help me