If I had to guess @Suzy81 it would have been sold to you as part of a package from Virgin Media.
The idea being that you take the sim and the VM part would reduce in cost to offset it.
Unfortunately it is covered in the terms and conditions that were agreed, hence the sim being sent to you and charges raised. Whether you choose to use the sim or not is up to you.
See this post that might cover it: https://community.o2.co.uk/t5/Discussions-Feedback/Default-on-Credit-report-Virgin-moved-an-unused-s...
All ways to contact o2 customer services are in the link below - this is a customer community, so we can't make any changes to your account.
Guide: How to find help & contact O2
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Link to our guide on how to contact them can be found here
