I was a liittle confused at first as the first two pictures show the metal pipe part seperated from the bendy plastic pipe, but thinking about it I think you mean the short length of plastic pipe attached to the metal bit. If it won't come off then it is bonded which makes sense or it would be in danger of leaking. I seem to remember it was the bendy plastic part that developed a crack and leaked so I see no reason why you cannot just replace that and connect new bendy pipe to the existing metal part in the engine if fully compatible. Alternatively remove existing metal part from engine, it looks a push fit, and refit both new parts. I am not a TDI owner so no experience whatsoever and treat my advice with caution; I am just using common sense.
