Check your settings under who can and why contact you @NotHappy1 as it is likely to be an o2 trusted partner, ie someone who o2 allow to access their customer database.
Most of these will try and sell you something you don't want.
You can also report the calls to o2 using the instructions in the guide below.
Guide: A Guide to Deal with Spam/Scam Calls and Text
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 Do not publish personal details (email, phone number, bank account).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
