The cost of an invitation code is 21 XRP. This article explains how Payburner uses that XRP. You can of course send any amount of XRP to buy an invitation code.
What happens to the extra XRP ? If you have sent 25 XRP or less for the invitation code, Payburner automatically funds your account with the entire amount minus an insignificant amount as explained here. If you sent more than 25 XRP, Payburner still only funds your account with 25 XRP.
Why? We've been hit by scammers in the past and lost XRP by refunding large amounts.
Can I get my XRP back ? Yes of course. Just open a new support ticket, tell us what happened, and provide us with any of the following:
- Your new XRP address
- Your invitation code
- The transaction hash you used to send the funds
We will fund your new account with the remaining XRP. We hope to remove this limitation in the future.