Hello,
I think it depends on where you are from; if you are from a relatively smaller city/town the MP's assistant will respond to your emails and calls. But if you are from a large city, then you might have to play a long waiting game as well.
There is no harm in calling to see when their office is open and visiting them (if you are able to do that). I live in a mid size town and my MP's asst emailed me back in 1 week and responded to my 2nd email with update from my file in 9 days.
I hope this helps.