Riding Lawn Mowers

We bought a new Husqvarna LGT2654 riding mower for a whopping 2600.00. The first time we used it, the belt popped off. We contacted Lowes and a Husqvarna service team. They said the warranty wasn't in effect because this was "USER ERROR!" Then we paid 400.00 to have it repaired by a Husqvarna recognized service team. We brought it home again after they fixed the bolt and put a new belt on it. First time we used it, it came off again! My wife was using our 10 year old Husqvarna mower and she did the yard in the time I tried repairing the "new" mower. Today I did exactly what the service tech told me to do, and again it popped off. This is destroying the new belt that I had. I feel I am getting a run around and that there is no other option than to use my old mower and go buy a new one from another company. I honestly feel this is a manufacturing flaw and NOT a User Error. Please tell me that you have a way to resolve this so my money isn't a total waste. I will say that unless this is resolved properly, this is our last Husqvarna mower or product to purchase.