Car boot issues

3 months back I went with my brother to collect his car there because he took it in for service. While I was there I decided to enquire about my book since well it was giving me issues. The guy that assisted knew exactly what was wrong with the car and he was correct because this was the part I have been having issues with. But due to financial constraints I couldn't fix the boot.

Then I make an appointment, took my car in for boot fixing. The following day just after they fixed my boot, the boot could not open until today. Its on and off. I went there to try and explain to them my challeng only to find out that they have replaced the wrong part , I honestly didnt have energy to argue because I could see that they really failed to do their job. Week passed by and the problem continued, I called them to try to talk to their service manager. I was told that the service manager is busy and they took my numbers and said he will call me back. Until today I haven't received any call from the service manager. I was told that I need to replace the part again and pay again, which I feel like it unfair because they decided to replace a wrong part.