Cp probleme with I9300

Hi evrybody im dialing with a big probleme on my s3
I keep losing the imei on my phone it gets all the time to nul/nul so evty tow days or 3 i need to back up efs and install modem MG3 to get my network
Im so tired of it ; there is any solution for this problème ?

Sent from my GT-I9300 using XDA Free mobile app