normally the companies that deal with digi dashes can change the milage to whatever you want
when i used a dash company i asked them to add 21000 miles onto a secondhand dash,i asked for
this so i didn't go past service intervals and cam belt changes
the guy told that was a first for him as most people wanted a reduction in milage, remember its
not illegal to have your milage reduced except if you falsely represent your car when selling it
to profit from it,as long as you declare the correct milage when selling thats ok.