If I understand correctly you exchanged the complete EGR unit for a refurbished unit.I should state to my defense I'm no expert and only have experience in electrical engineering. So diesel engine optimization and know how is not my baby's. I'm not sure what intention the change of belt and pump change would achieve with a egr either, as I said previously I'm a novice on diesel. But I learned after reading the articles here and other forms I'm in process thinking that anyone with out a idea is getting fleeced. Possibly it's a money racket or dealership issue. I've no idea.
Finally it was offered to me by small garage to blank for 200 euro or exchange the unit. I did the later. It will be interesting to see what others think and if the engine light of doom reappears.
If it has been cleaned correctly and all seals and electrics are good you should get similar service life to the original. The EGR is going to block on all T6, it’s an unavoidable fact, how soon is the only variable.