Hi,
Other option is contact support
https://support.chess.com/article/346-contact-us
Thanks
Two months ago I paid $79 for platinum membership. Two days ago I upgraded to diamond at $119. You all charged me the full $119, and did not give me credit for remaining $79. Fix this.
If you purchased through one of the app stores, they handle the payment process. If that's the case, check the app store transactions and you may see that there was a refund for the original purchase.
The app stores don't handle updates like purchases through the site do, as I understand it, and don't do a discount. That is an app store thing and not influenced by the site.
If you find that's not the case, after checking, a ticket with support, as mentioned by @AndrewSmith us the next step.
Two months ago I paid $79 for platinum membership. Two days ago I upgraded to diamond at $119. You all charged me the full $119, and did not give me credit for remaining $79. Fix this.