shadowfax

Hi, I have a (almost 2 year old) Mazda 3 sport/nav obviously still under guarantee, around six months ago the tyre pressure warning light came on accompanied by 6 loud beeps whilst driving..I went to the Mazda main dealer who said they'd fixed it, few days later it happened again, went to main dealer who said they'd fixed it again, few days later it happened again, (once this has happened it stays on all the time and beeps at me six times on every start up) I went to the main dealer again and they said this time they really have fixed it...the problem never happened again until I took it for a service last week, 2 days after the service the problem appeared again, making me think that the root of the problem had not been fixed but somehow they had turned it off and during this new service they had maybe unwittingly turned it on again, so now I have just returned from the main dealer, they did a reset and the problem has gone but I am sure it will return in a few days..just like last time....given that the main dealer seems reluctant to fix it properly, (I seem to recall that last year they said it would mean replacing the whole computer part of the car but am not too sure after all this time) what should I do?
has anyone had this problem? any ideas out there please?

thank you for any replies,
best, Kevin