The Curse of the Broken Microwave

I now believe this house came with a curse on it. We have gone through two perfectly good microwaves in the last year. The first one came with the house - it's a built in microwave/oven combo. Great idea until one of them breaks... near 2k to replace entire unit, which is just throwing money out the window when the oven works just fine. While we were in the process of shopping for a new microwave, someone at work offered Eric a freebie. It was a GE Spacemaker that fit over the stove, was stainless steel to match the rest of the appliances and brand new, still in the box. We gave him $40 for it because we felt bad taking it for free. Eric installed it last September. Just this week, the magnatube went out. It works like it should except that anything you put in it gets no heat whatsoever. Unfortunately, since it's a "freebie" and a "hand me down" at that, we can't get it repaired. The GE repairman said that without the serial number he can't work on it. It's basically a worthless piece of junk. Are you kidding me??? So, we are in the market (again) for a new microwave - an over the stovetop model would be best - any recommendations???