Porsche Silver Spring

My low-mileage (50K) 2004 Cayenne S wouldn't start after a few days sitting idly in my garage. Porsche of Silver Spring service rep. told me I needed a new battery. It cost me $667 to replace the battery, which is inconveniently located under the driver's seat. Five weeks later, the new battery was dead after a few days sitting in the garage. Took the SUV back in for service and after 13 days Porsche of Silver Spring still couldn't tell me definitively what the problem was. But the service rep. was 100% certain the current problem had nothing to do with the battery Porsche of Silver Spring had recently replaced. His best guess/estimate was either a bad generator or bad starter that might cost between $1,300 -$3,100 to repair. But I would have to pony up some more $$$ before the service technician would know for sure what the problem was. I was fed up with the wait time and poor communications and declined to authorize any further repairs. I also asked that my $667 be refunded because it was obvious to me that replacing my old battery hadn't resolved the problem. Porsche of Silver Spring service rep. told me he didn't think a refund was warranted. He told me he would go look for my old battery and reinstall it and return the car to me. This was after his repeated assurances over the prior 2 weeks that my old battery was no good. Assuming he could even locate my old battery, the notion that a so-called reputable Porsche dealership would condone installing ostensibly damaged parts on a customer's vehicle is ridiculous. That remark alone was sufficient justification not to continue doing business with Porsche of Silver Spring. This is the same dealership that sold me the SUV for $60K. I had previously purchased a 325i from their associated BMW dealership (no problems there). Needless to say, Porsche of Silver Spring won't get any more of my $$$.