Wrong amount charged for marketplace plugin

I sign up yesterday to download Marketpress clicking on the 19$ options and at the check out with pay-pal was showing up the right amount but as soon as I finish the transaction I received an email confirming a transaction of 79$. I think something wrong happened because what I asked for was the 19$ purchase. You can see from my account settings that I have no subscriptions at all so clearly I asked for the 19$ option. Is it possible to refund me of the difference? I wanted to get the 19$ to try your awesome product I really hope that you can help me with this.

thank you very much.

Luca