I think he received an auto-reply email after initiating the purchase, but he hasn't received a response from Apple Developer Program Support. This is the same issue I'm experiencing. Luckily Apple Developer Program Support replied to my email, however they keep saying the same thing but the same result occurs, nothing. Here is their response to my payment not being processed:
Hello #####,
This is Claudia from the Apple Developer Program Support again. I hope you are having a wonderful weekend.
I would first like to apologise for this delayed answer. It is certainly not the normal waiting time for an answer from Apple Developer Program Support. We are currently facing a high volume of emails from our customers and your patience is well appreciated.
We’ve withdrawn your previous enrollment (#######) so you can reenroll with the Apple Developer app now.
Should you have any queries in the future, please do not hesitate to contact me directly, simply reply to this email. We’re more than happy to help.
Your case number is #####
Enjoy the rest of your day.
Best regards,
Claudia
Apple Inc.