Thanks KT,
"I wrote an email to Apple and they responded the following:
Thank you for contacting Apple Developer Support regarding your request for a refund.
We have processed a refund for your order as an exception to our no refunds/no exchanges purchase terms. Although we have processed your refund immediately, we ask that you please allow 5-7 business days for the credit to post to your cardholder account.
If you have any questions or need further assistance, please let me know."
Now on developer.apple.com under my account, it says "enrollment pending". My question is: what should I do now? Should I wait a few more days or should I try to set up a new developer account with a new Apple ID which is also different to the Apple ID I'm using for iBooks in iTunes Connect?