No access to mobile network, tried stock rom and CM

I previously had issues with my GT-i9300 using a stock rom where it wouldn't boot past the Samsung screen and in recovery mode it was showing an EFS mount error. I managed to fix it with a file I installed through Odin. I then installed CM through the installer and it all worked ok other than my cellular access. I then installed a stock rom I found and I could see the mobile networks but still didn't get a connection. I then installed cm-10.2.0-i9300 but I still have the same problem. Now I can't search for any mobile networks and neither is it connecting to anything. I've tried putting it into Airplane mode and rebooting but that didnt work either.

I installed GetRIL and it shows I have baseband and RIL mismatch, but when I install other RIL's through the software, it still doesnt fix the problem.

Can anyone help!?!?

I did have a detailed look but couldnt find any working solutions for my problem. I realised it was linked to my IMEI being corrupt, so I reset my IMEI with Chimera Tool and now it's connecting to the network but is still problematic. It doesn't always connect calls and I have no mobile data at all.

Any ideas on where I can go from here? I don't want to give up having come this close! :crying: