Can't update on ota on samsung galaxy s3 ( t999l)

Yeah, so here is the promblem:recently just buyed my galaxy s3 and tried to update it over the air (ota) cause I knew that my 4.12 version is way behind. But every time i try it always say its up to date while its not. I have have not downloaded any custom roms BBC or rooted the phone. Its the t-mobile and in yop condition. Thinking of doing it on kies but wanted to ask you guys first. If you know of a store even better.