renault approved service department damaged my car

I took my car to renault automall for a service I told them too adjust handbrake when I got it it was not done they said I can bring it again my next time when I got the car back it had a part by hand brake broken I showed them they apologised put part on wrong way I phoned back 2 days later said I must wait for the part from France I then called back as my mat had 2 feet marks on and by the feet marks the mat had disappeared like something ate it I lift up the mate too see it had gone down to my car carpet itself what do I do I am devastated I am old and a single parent and this is my car till I pass on and the garage had now ruined it and nobody seems to care and I am still waiting for a reply so my renault sandero is not how I expected it to come back. Please what can I do