SIM network unlock PIN and not registered on network
I switched my SIM as requested at the start of June and it's been working for a month without asking for a code and all of a sudden it's asking for a SIM network unlock PIN and telling me I'm not registered on the network. I tried the 7890 code I found on the website and when that didn't work I filled out the Mobile Unlock Code form. It's been longer than the 72 hours stated as the response time and I've heard nothing back.
I tried calling but an automated voice said call centres are closed due to coronavirus. What am I meant to do next? This is the only other way I can see to get in touch with anyone.
Could someone help me please? It's getting urgent now.