Thank you, that's what I have been doing, but it doesn't work unfortunately. I get an automated response each time I try that, and when I called them, they said there is nothing they could do, even though the unit has not shipped yet.

"Thanks for contacting Google Play regarding cancellation of your order. All orders are processed directly after your purchase is complete. As a result, this means that there is a very short window of time to cancel an order prior to shipping.

Although we attempted to honor your request, we were unable to cancel your order in this window. "

Whatever that "window" is, it seems longer than 10 days!