What does your Transactions page say about your recent payments?
What does your My48 account dashboard say about your current membership plan status and expiry date?
Does your Buy Plan page list any stacked upcoming membership plans?
Was this your first plan purchase?
If so then you will have been charged €12.99 for the one-time activation fee plus €12.99 for the plan itself.
If you need to contact 48 support about this then see the links in my signature below.
