Run flat tyres

I have now lost total confidence in my mini clubman estate, when I bought the car I was not told that I had run flat tyres and if they had told me how much they cost to replace them, I would have walked away from buying this car.
So far I had to replace three of my tyres , the first one was 3,000, then 13,000 and 15,000 miles, the last two occassion I had to do long trip and ended up paying over the odds £180 each time.
In September 2012 my lease will finish and I WILL NEVER EVER BUY ANOTHER BMW OR MINI and have told all my friends, that I cant use my car for long distance any more.
I really HATE this car.