Iphone repairs

I took my Iphone to have the speaker replaced on 7 October. Then the tech damaged my screen, they replaced same day. When I got home the screen started playing up and i mailed them that the phone is worse as it had vertical lines and became inoperable. On the 14th I took my phone back to WeFix and they replaced my screen again. When I got my phone back the screen was much duller and actually had a blue look to it. I have emailed them since as a generic part was installed on my phone and I am not happy as I have had no work or parts replaced on my phone since they replaced the speaker. Nobody is getting back to me as to how they are going to resolve this issue. And I am now at a stage where my Iphone lost its value with the **** they installed.