I've had the same experience with Mr Wragg - I've only written to him a handful of times, but he has never replied, so I don't bother now. Maybe he knows I don't vote for him
But what admin writes makes good sense, and is consistent with what we know about the way Wragg works, i.e. that he likes to publicise his own association with community organisations and campaigns, such as the excellent Friends of the Memorial Park, or the campaign to improve rail services at Rose Hill.
Personally I think Wragg is making a mistake. It wouldn't cost a huge amount to employ someone extra to deal with his correspondence, and it might well make the difference between him retaining his seat and losing it at the next election.