We Are Having Trouble Starting Our Srx.

We purchased the 2011 SRX in Aug. of 2011. We started having trouble getting it to start in  2012. We had to have it towed twice...the first time they kept it a week and the second time they towed it they kept it for over three weeks. We also had it taken in one other time for the same problem. Now they are saying it is fixed after having it for 3 weeks. The dealership has been very kind to us, but We are in our 70's and need a car that we can depend on..that is why we bought the Cadillac! I no longer trust it!!! Please help!! I am scared to death that we will get stranded someplace with a Cadillac with 12,000 miles on it that will not start for us!!!!!! Yvonne McManaman,