Very poor service and refusing to give money back.

I was referred to Quintin at Q-Tech Performance after our Peugeot CAT problem could not be sorted. I phoned Quintin and on voicemail he confirmed that the Air Pollution and CAT problem is the same and he can get it sorted. He quoted a hefty amount but we decided it will be worth if it works. He also said and I quote' my work is guaranteed if it does not work bring it back or your money bac'k'. I have the voicemails. Good and well we took it in to Brackenfell 30km away. Got there and explained again the problems and left the car. I got a message later to say car is ready and fine no Cat problem will come on but Air pollution will come back when injector misfires. I said there before we paid I am not .happy as nothing was fixed. He said I fixed it that the Cat won't come up anymore but you need to get it to a Auto electrician to check the intermittent fault. On the way home the car came up with more faults than before. The Air Pollution as well as Catalytic converter fault. My husband filmed it and I send it to him. He kept on saying he did fix it. I send him the video where it shows. He is refusing to pay back the money even though I offered. Hi an amount for his time taken . I informed him that I will take measures as I cannot accept such service and taken a person hard earned money and not taking responsibility