Ebay Ritz Camera reports purchase returned to MS Live.com's Cashback. Why?

I purchased a Tamron 18-270 through Ritz Camera on Ebay at the end of November of 2008. At the time MS Live.com's Casback was running 30%.

The purchase went through without a hitch and I received the Cashback payment at the end of January. It was about $180.

Yesterday I received an email from Live.com telling me that Ritzcamera had reported the item returned and refunded on January 28th, the same date the Cashback payment was made to me. I did NOT return the lens for a refund.

I emailed Ritz but I have yet to receive a response.

It appears that I just have to jump through a few hoops with MS Live.com to clear this up, but I'm wondering if anyone else has had a similar experience.

I assume serial numbers were involved? Just take a picture of the lens with the S/N showing, next to todays paper showing the date. Send it to them as proof you still have the lens.