I used to work in a Government Dept and we used to get TDs forwarding us letters and applications for all kinds of things. Believe me, the fact that a TD had made any kind of representations on a constituents behalf made absolutely no difference whatsoever. The rep was never even seen by senior officials or the Minister and just received a standard response while the application or whatever went through exactly the same process as that from Joe Soap with no TD to lobby on his behalf.
Seriously, Civil Service offices receive hundreds of reps every week and would never even think of bending rules or skipping people up a queue as a result. They're just acknowledged and then it's on with business as normal.