How many days were between you paying and the email arriving @Chloe93 ? It might be a cross over (the email being generated while the payment was clearing).
If you log into your account does the payment show now?
Finally are you sure the email is genuine and not a spam/phishing email?
Advice on the last one here: https://www.o2.co.uk/help/safety-and-security/phishing-and-smishing-advice
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here
