Trouble with login and need a PUK code.

I need a PUK for my SIM card, to use in another phone. I am having difficulty logging into ID mobile, my email and number which I thought were registered (as I was able to login without trouble on the app using my original phone). I am trying to login to use LiveChat to obtain this, but cannot login, despite me previously using the app.

Apologies if the above is confusing:

1. My phone touchscreen froze
2. Have a donated phone to use.
3. Put my SIM card in, but was asked for pin to unlock (which I do not have)
4. Tried several searches, now it appears locked.
5. Wanted to use LiveChat to request PUK.
6. Cannot login to IDmobile on my iPad, as saying details incorrect, but can’t see what this is. I used the IDMobile on my phone to pay bills, logged in without issue.
7. So now, can’t even login to IDMobile website. My phone number and surname and year of birth all correct!