I don't know why that happens but it's a known fault, your account is credited but not upgraded in unusual circumstances. Anyway Geraldine told me what to do and you should now have a voucher code in your email inbox, and account balance is now zero.
Just use the voucher to upgrade your license to S2.
Thanks, Scawen
P.S. I'll let Victor know about this so he can maybe fix that small bug.