Sim switch / new contract / no access :( please help

[Kait]

I switched from a sim contract to a new one that was cheaper since I barely used the one I had since I was only using it to call family. Plus I don't have the money for it. Had some trouble for a while trying to get my number switched over to the new sim + contract. I can't access the sim/number on my O2 app/account and no matter what I do I can't get into it keep on top of my payments, O2 made an error in Dec and fixed it by sorting out the payment. Now I'm being charged £60 when it was supposed to be like £6 a month, it's now put me in overdraft. Is there any way to get into my account and sort this out? I would call, but I have really bad anxiety and can't talk on the phone and the people I've already talked to that were handling the situation before weren't helping at all, I can't access anything to actually contact them again and I don't know what to do anymore.

[MI5]

@Kait 

Can you log in online https://mymobile.o2.co.uk/ ?
If so, try deleting the app, rebooting your phone and then reinstall the app.
We’re just customers like you but it sounds like you’ll need someone to access your account which can’t be done from here. If you message O2 on Facebook (https://o2uk.co/O2CFB) , Twitter (https://o2uk.co/O2CTW) or Instagram (https://o2uk.co/O2CIG) , they should be able to help you with this
Thanks

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