So i took in my car for a wheel bearing the other week, and it took 5 days to replace, whilst they told me i had a cracked knuckle which i asked to have a look and low and behold no crack on the knuckle, I took it in again for a sensor replacement because an air bag warning light had come on, they then told me my airbag from my seat was missing, but i only just recently got this warning light, During this process they have mucked my tracking up and now my digital fuel display is miss reading, i have a full tank which used to say around 450 odd miles (i have a diesel) now its halfed it and says 270, could someone tell me how to reset this or correct this on my own, as i feel that i cannot trust this garage with my vehicle and don't want anything else to go wrong!. If theres a simple solution like the trip computer button could you tell me please? cheers guys!

As far as I'm aware you can't reset the 'miles remaining' gage - it will do it itself over time.

You could try resetting your mpg, the miles remaining is based off of this figure. To get it that low though, they must have been going bonkers on the accelerator or something.