I was a independent company advertising on Facebook called Nats Mobile Repair Service that did the repair

I have a Samsung A5 mobile phone which I stupidly managed to smash the screen on at the beginning of the year. I took the phone to have the screen and LCD replaced. I paid £90 and was given a 30 day guarantee. 6 months later the screen is coming away from the phone and the sensitivity of the phone is very temperamental. I got in touch with the person who fixed the phone and they have refused to help as it's past the 30 days. Now I am stuck! I don't feel I should pay for another repair when a bad job was done to start with. Can anybody give me and advice please. Many thanks ☺