I'd go up the chain of command and forget about the rep.
Contact Medtronic SensorRestor Neuru Stimulator directly by calling and or emailing anyone in the management or sales until you get some responses.

Or if your medical ins paid for most of it perhaps contacting them for assistance as they paid for something that is not safe or functional.
Surely there is a warranty for possible defective units?

But it sounds defective to me. And you shouldn't have to suffer when they got paid for it.