contradicting Mileage figures in PCP Pre- contract information

[Eddiejonesus]

VWFS is charging me extra mileage charges following a VT. However, my pre- contract information has a yearly limit of 10’000 miles and my actual contract signed has a limit of 5000 miles per year. They have rejected my complaint and claim that they can only go by the mileage in my signed contract. My question is that surely this whole contract is null and void if they mislead me with inaccurate information in the pre- contract agreement? Doesn’t this information have to match up in both documents? I’m referring to Ombudsman. Thanks