How can I confirm the date of cancellation, if the app is no longer to find on the purchases lists?

Hello,

I had an unexpected charge for an application, which I cancelled in the test phase. But in the next month it was billed, because the developer said the cancellation didn't happen before the new month starts. The problem is, I can't find out the any history in the purchases, maybe it is because I had deleted the app after I cancelled it. So I want to know if there any way to find out the app cancellation time. Btw, the app didn't send any information after cancellation, this happened for a second time. THX.

Regards

Ingiu