Can't make calls and loss of credit

[PhotographyAli]

I've been having issues with making and receiving calls and sending and receiving text messages. I assumed it was due to lack of funds so topped up my phone a few days ago, which I then discovered I already had £9 on the phone. 

Since then I questioned whether it was because I was using an EE sim card in an O2 set, so have gone through a process to get the phone unlocked.

I recently tried again and it's still doesn't seem to work, and when I try to phone out it says its due to lack of funds. Which I know isn't true. Having recently topped up, I had up to £19 

I would appreciate if any one (possible from EE) could help sort this issue out or give me the needed advice. I need this phone for work. 

[XRaySpeX]

What does texting AL to 150 from your no. fully report verbatim (it is free)?

[bristolian]

Does the phone show coverage indicators? That would rule out an issue with unlocking if so.

A hibernated PAYG phone would show coverage but outgoing calls would all be diverted to CS, incoming calls & texts would fail.