other explanations
it could be that the VS staff member received M&S vouchers from Joe Public as a thank you after untangling a particular nasty complaint. It would be hard to prove collusion in this case. We've all sent flowers etc to somebody after they've gone above and beyond to help fix something.
Now if there was a pattern, here's 10K mile, oh there's a voucher, over and over, then that's different!
Could job we retain the adversarial system of justice administered by our peers, and not just judge based on a newspaper story!
G