While you may have slow 4G or 5G O2 is a totally different provider so signals can be different. 

IDMobile uses Three and Vodafone network.

Joe

Hi ​@capnmetal,

Thank you for reaching out to us, please accept my apologies for the inconvenience caused.
Please use the following link to check the coverage in your area:
Mobile Coverage | iD Mobile Network
or try to reinsert your SIM, or try your SIM in another phone. This will determine whether the issue is with the handset or with the SIM card itself.

Thanks,
Hosai

I tried replying to you ​@Hosai W  however realized it didn't go through because the signal was really bad. None of those fixes you highlighted worked for me. Thought it was likely an issue with just Stratford and zone 2-3 east London, but then I travelled West yesterday and had the same issue.

I've switched to another network and haven't had issues since.

Hi ​@capnmetal,

We’re really sorry to hear about the signal issues you experienced, and that the troubleshooting steps didn’t resolve the problem for you.

We completely understand how frustrating this must have been, especially when the issue continued across different areas. We’re sorry to hear this ultimately led you to move to another network.

If there’s anything outstanding we can still help you with, or if you need any further support in the future, please don’t hesitate to let us know.

Regards,

Gemma M

The iD Mobile Social Media Team