There's just no need, other than "behind the keyboard aggression syndrome" , to assume the vendor was trying to rip off the customer. Mac's is a pretty big outfit and not likely to have a business model based on rip offs.
The problem could be with the manufacture of the part, installation issues, as mentioned damage during modification, incorrect part shipped by accident or probably some other causes we haven't thought of.
So let's calmly wait until Stillrunners does what he should have done in the first place-call Mac's and see if the problem can be fixed. It does no good to ***** about it here at this time, although Brent has,as usual, offered some good insight. Let's just put away the hanging ropes until we have a bit of real information and not just speculation. Ah, the drama...