At&t Samsung Galaxy s6 edge

I am in india with an unlocked At&t galaxy s6 edge and after all the fuss about the update and many of my friends getting the 5.1.1 update I am still unable to get it. I mean I have constantly checked whether it was my network problem but that's not it neither is my WiFi connection bad. Besides the phone is getting very laggy all of a sudden. Don't know what to do. I even went to the Samsung showroom to see whether they could do something about it but those idiots here don't have the slightest idea what to do. If anyone out there has the same problem and have solved it please reply.

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