I’ve left 02 but received a text for a remaining bill

[1028055332]

Hello I have left 02 recently, but I have received a text message from you saying the following, 

Hello John, Your bill for account is £0.05 this month. To view it, go to www.o2.co.uk/myo2/viewbill. Turn off your wifi and you won't need a username or password. You'll need to pay by 18/04/2024 and you can make payment in My O2. Thanks.

we need to pay this 5pence so that it’s off the old account but I have rang and spoken to customer service they say my account no longer exsists, also I cannot log into my account via the app or via the internet because of the same reason, my details no longer work to allow access to pay, please can I pay this remainder balance. 
Thank you.

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[MI5 · Accepted solution]

@1028055332 

You can get in touch with Payment Management team on 0800 902 0217
Payment Management opening hours:
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Saturday – 8am to 6pm
Sunday – 9am to 6pm