Is there any right to Paypal to convert currency at their discretion?

[William_Min2011]

I purchased an item which was posted by US$.

I chose my US$ MasterCard to pay for it.

If Paypal requested payment by US$ to my US$ MasterCard, I don't need to pay conversion fee.

But Paypal converted my payment amount as CAD$ at discretion. Then MasterCard converted again to US$.

Is there any right to Paypal to convert currency at their discretion?

This should be claimed by all currency conversion victims.