How to unblock a reserved pro-site ?

Dear WPMU DEV Support Team,

A client registered for a pro site but an error occured during the processing of the PayPal payment. The client tried to start the registratiion again but received a message indicating that the USER NAME, EMAIL ADDRESS and YOUR SITE is already reserved (I assume for 48 hours).

1. Looked for a way to access the registration / payment option again, but I did not find this option
2. Deleted users, cleared browsing data, tried to register one of the clients, but still receive the same error message as above
3. Checked the WPMU DEV support forum
4. Ran the WPMU DEV Troubleshooting Flowchart

Would you please share if there Is any way to unblock reserved pro-sites or do my clients have to wait 48 hours?

I thank you in advance for your kind support in this matter and send
plenty of sunshine
Cherie : )