how long waiting for MRI?

I have posted before about the fact that I saw my new neuro on April 18th and that he ordered blood work that had to be in before scheduling my other tests. I was told that I would be called when the results were in and the MRI would be scheduled.  No one called me. The first time I called, the receptionist said that my results should have been in before then and that she'd have a certain person look into it and call me back which she didn't. I have been calling and leaving messages for the lady they say is supposed to be handling my case.  She has yet to call me back.  I've left 5 messages in a 2 week period and have heard nothing from her.  When I called yesterday, the receptionist put me on hold and looked up my records.  She said that my blood work was all there and was perfectly fine and that (the lady who hasn't returned my calls) will call me with scheduling for my MRI.  I don't want to be a pain in the neck, but I am anxious to get the testing going.  How long is normal to allow for the MRI to be scheduled?  I don't want to be a pest, but I don't want to wait around for nothing either.  My husband is changing jobs at the end of the year, so I don't have time to waste for that reason in addition to health reasons.  I'm going to call my insurance company today and see if they have approved the MRI and the neuropsychological test so that I'll know if the delay is waiting for my insurance approval or if it's the lady that hasn't returned my calls.  I try very hard to cut people slack, but I think it's awful to not return someone's call like that.  Even if it was just a short message that she didn't know anything yet, I think she should have called me.