Galaxy S3 GT-I9300 install stock ROM

Why is it so hard to find the right ROM ? This is where my brain goes into panic mode!

How can i tell witch ROM to install? tried several that seemed to be the one but cant get carrier working!

Bugth the phone in Denmark without a carrierplan.

Phone info?

model: gt-i9300
fcc id a3lgti9300a
ssn -i9300gsmh

How can i tell from this what ROM i need ?

Can Samsung tell me from the ime or s/n number ?

Have usb-drivers, odin and access to SAMmobile and know howto do it (flashing etc..).

Can someone plz just link me the right ROM or tell me how to get it ?

Thx alot there will be cookies and rep to whoever helps me !:good:

Resurrection Remix custom ROM Samsung GT-I9300 issues

I have an issue with my S3 which follows by camera error,battery drain and slow processing of the phone.
Kindly provide with a solution.
Thanks