Tire Surprise:(

Gosh I had planned on spending today quietly.
Well...
Driving home after having my tires put on, the sensor light popped on alerting me to low tire pressure. Drat. I then turned around and went back to Costco to have tires checked. The service guy went back to the bays, returned and said don't worry, it often happens with a change of tires and light will probably go off. They didn't bother to check the pressure. (It didn't go on the last few times I had tire changes)
So,
away I drove again with light still on. Got home, had a cup of tea, wrote my blog post and then daughter set off in the car to school. NOT.
Door opened and "Mom?The back tire is flat as a pancake and the passenger one looks flat too!"Yep.
So,
I call Costco tire service and get an answering machine over and over. Called administration and explained and they said wait for a call from tire service. Meanwhile I call CAA to come and give me a tow or fill the tires. Soon Costco calls back and says bring car back and we'll look at it. Half an hour later the nice man from CAA arrives and fills tires with air and follows me to Costco to make sure they stay inflated.
So,
at Costco the mechanic tells me that it is the tire sensors, 3 of them are faulty! They are all causing the tire to leak. What! I drive in and they are fine I leave and they are not? He says it's random and they can go at any time. This car is 2 years old. He says nothing they can do and sensors are under warranty so I should go to dealer.
So,
I call dealer and they say maybe December 7 they can look at car! I say "Wait a minute, the sensors are under warranty." They then say, bring it in and we will see what we can do. ( I have to take it there because the tires are flat and won't stay inflated)
So,
Costco mechanic fills the tires overfull and I drive there petrified that any minute I will be driving on rims. Get to dealer and they all come out to look at car and exclaim over the fact that the tires are inflated to 36, way over limit but I say they did it so I would make the drive here. Tsk, tsking and making it pretty clear that they think Costco damaged the sensors, when prying the tires off the rims and if so, not under warranty. If I had had them done at the dealer, it would be covered etc. Only covered otherwisw if defective.
So,
Costco says they didn't and GM says they probably did...... but we will have wait until they have a good look before they can tell me anything. I will be charged for the dismantling and rim cleanup no matter what.
I am pissed. Sensors cost about $100 each and they absolutely have to be replaced. I hope they are defective and under warranty otherwise I have a big fight on my hands:(
Does seem rather suspicious that I drive in fine and leave with problems. 3 sensors?
So,
I think I need another cup of tea and will get back to what I was doing um, about four hours ago now...... honestly what do they say about best laid plans? Sorry for the odd post but I am venting....

UPDATE: 24 hours later, I get my car back. The sensors are fine, not damaged ( whew) BUT they had obviously been jostled and this is what led to the air leaking around the base of the thingie you put air in. Charge for cleaning rims and resealing, $113. Sigh. Time lost and upset = priceless.
So,
tire change at Costco is the culprit. Next stop on this journey is back to Costco. I wonder what will happen now...