True, but there's no way of knowing if the old one is fine and the garage are just incompetent.
Again, true, but I feel like a half decent garage wouldn't have any problem sorting it.
Does the car not have to be present when writing to the TCU?
That would be the litmus test, but it's not as easy as a simple plug and play swap I don't think.
In any case, I've told the garage to go ahead and use the new TCU for which I will contribute half - hopefully this will be the end of it and I get my car back, but something tells me that won't be the case.