What do you see under My Account/Bills & payments?
What might you have bought?
The amount seems like a broadband subscription.
But Live Chat should be able to tell you:-
Get in Touch (all the options, and the best place to start):-
On a screen with big buttons all around, you may find the link you need is under a tiny green arrow, so be vigilant.
Live Chat and Send Us a Message:-
On Live Chat, when you can get onto it, keep your answers short, sweet and prompt, or it will time out on you.
If the person you are talking to doesn’t seem able to understand your issue, ask to be escalated to the next level of help.