I spoke to GMH customer assistance 1800 number a year or so ago, with details of a van I have, & when he heard the 8WM70 code he said "are you checking if its a sandman?" sarcastically like he spends all day doing this. When I got the report back, it said stuff all, I don't think it even confirmed completion date or original engine number, which is what I was after.

cheers
Max