Ads mis-redirecting to my site

Left my wallet on a train last week. I cancelled all my cards within a couple of hours, but it was a pain in the arse as it meant I had no cash and no means of getting any cash for days whilst replacements were issued. Hence me putting a free tracker on this site rather than a professional one (no means of paying for it) - I wanted to know who's looking at the site. Turns out, about 10 people an hour were being referred from the Royal Mail website! I couldn't figure out how or why, so I emailed them and they couldn't figure it out either, despite the evidence. Turns out that a rogue error was causing some banner ads for a loans company to direct people to! Such a shame they didn't stick around when they got here. The girlfriend's gone to V festival this weekend with her brother. She didn't really want to go, and by all accounts she isn't enjoying it very much (very few decent bands on the Saturday in Staffordshire, and she hates camping), and it's really expensive (£2.50 for a bottle of water) and now she's worried she can't afford the train ticket home! I'm sure she'll get back ok somehow, though how I'm not sure.