I had a "mileage correction" fix to a customers Scenic display.
It had jumped around 50K.
It cost me £80 to correct the mileage, all back to as it was before fault.
It is not illegal to alter/correct the recorded mileage.
However if one mis-represents the mileage to a purchaser of that vehicle then that is an offence.
I have since found the last MOT for my fathers car, it had 75K on it on 31/12/2008. He only drove the car until the end of June so I would estimate the mileage to be about 82/83k (he normally did around 15k pa). Quite amazing how it jumped to 163 or 167k, i can never remember what it is.
Will have to find someone in N ireland to get that changed ASAP.