None

I had no idea that someone who repairs PCs could also dictate what products a client is allowed to use?

The client was discussing purchasing products with another vendor.

He took it upon himself to tell the client, "No, if you're going to do it, you have to plan the whole thing; you can't just do one part."

So whose company is it, his or the client's?? He made a decision for the client without authorization—if there's a problem, are you going to take responsibility for it, buddy???