I am in dispute with a dealer.

I returned a used Mazda to them on the grounds that on three occasions the engine management light came on, the car lost power on acceleration and downchanges on the auto box became difficult.

The garage is now saying that a faulty oxygen sensor does not make the car unfit for purpose under the Sale of Goods Act as it is repairable, is that right?

And secondly, although the car was put into another Mazda dealer some 300 miles away on the third fault, under the agreement of the original service manager, they are also saying that whatever the other garage did is nothing to do with them. Any views on that please and advice? the whole sequence of evnts happened over 10 days from date of purchase.