Can't add a PAYG sim to my existing my O2 account

[RichNotts]

I currently have 2 pay monthly sims on my o2 account. I've recently ordered and received an O2 payg sim for my son, but when I put it in my phone to activate it it doesn't show on the my O2 account, I can only see my two existing sims on there. I went onto the O2 website but when clicking the link that says 'add products to your account' it says page doesn;t exist.

I just want the new payg sim to show in my O2 app so I can add and top up balance. How do I do this?

Thanks

[MI5]

@RichNotts 

You can't do that yourself anymore.

You either need to register the sim for its own account using a different email or contact O2 to see if they can add it to your existing account.

Guide: How to find help & contact O2 

[pgn]

Note you do not need to register a PAYG SIM to any MyO2 to top it up, @RichNotts 

Other ways here:

Guide How to Top Up (PAYG) 

Otherwise, follow advice already given. Good luck!