Ourisman Chevrolet Co. Inc Car will not stay started Marlow Heights, Maryland

on 2/13/2012 car would stay started, it was towed to my mechanic. he advised that the security system needed to be reprogrammed which could only be done by the dearlership. we were able to drive the car to the local dealership Ourisman right around the corner. It stopped in their driveway, was then advised by a repair rep, no need to have it looked at, they will tell you that you need a engine, get it towed out of here, we will help you push it, into a parking space, then call your tow truck. that didn't happen, they walked away and left us standing there. a salesperson had to come to our resue and get the repair dept. to acknowledge us. i asked that the car be looked at, hook up to the computer or manually find out what is wrong, later that day, they said  the igintion must be replaced cost $684.98, gave authorization and had the work done and paid for. My daughter picked up the car and less than two miles away it stopped again. we were advised to have it towed back. the next day we were advised that now i have a new problem, new? when a asked to have the car checked at first and fixed. well,  now after the second diagnostic, the fuel pump and filter must be changed, cost $1507.00. total cost $2191.00. i came and removed the car from the dealers after I had to pay $128.00 diagnosic fee. I have since taken it to my mechanic, who is fixing it,  parts $270.00 and labor $200.00.