No network connection says temporarily unavailable

[#1]

Hi, I've had no mobile connection for a few days I have tried another sim and it works great on a different network.  Having had problems contacting Plusnet I eventually managed on Chat, I had enough by then and said I wanted to cancel but at present I've  paid for a service that hasn't been there. I need my phone access until I can arrange alternatives. 

[#2]

I fixed it but I do think the problem was caused by the changeover to EE.

On my sim I changed settings to Plusnet and it worked, thanks to another post. I certainly hadn't changed any settings to have caused it but it was showing EE only.

I'm far from impressed with these circumstances and will still be moving on.