I purchased the "Apple Developer Program - Membership for one year" since a week ago, and my status is still pending.
I haven't received any update since the purchase... What should I do? Who can I contact?
Apple Developer Enrolment
I would recommend you to contact the developer account support at https://developer.apple.com/contact to make sure they are aware of the issue as they do not monitor the forums.
Albert Pascual Worldwide Developer Relations.