Who do i need to fix my media wall?

Hi, It's difficult to comment from your description of the issues. Unfortunately you may struggle to find a trade willing to fix problems caused by others. Is it that the project, crosses too many fields and the person you hired, cannot achieve all or any? Media walls are something we commonly build, but do not get involved in the electrical elements or the plastering element etc. Would you be able to talk with your previous trade. Perhaps it is a misunderstanding of what was needed or something that can be rectified by them if explained the issue. If it is outside their skill set to put right, you may need to look at other individual trades to resolve the issues. Better a master of one, than a jack of all.

You actually need an audio visual specialist. Ask them for a call out fee to come and have a look.