Some payment methods might take up to 48 hours to be confirmed on Xsolla's system. If you are using an instant method such as credit card and the problem persists, you must talk to Xsolla's support about it.
To contact Xsolla, open the Gift Shop in game, click on "Get More Reward Points" and proceed to the page where you choose the amount of Reward Points you would like to obtain.
If you are on PC, you will see a purple chat bubble at the bottom left in this page:
If on mobile, it will be a button at the end of the page:
If contacting Xsolla does not solve your problem, contact our support on Support Request > Reward Points Issue with a screenshot of their answer.