Airtel — sim swap problem

Address:

Bangalore, Karnataka, 560068

Dear airtel,
I am trying to upgrade my sim from 3g to 4g i followed all the process like send new sim details to 121 and replay on that after that i am not getting confirmation call from your end and every time after 2-3 hr i get one sms like could not be processed as we did not receive any confirmation from your side. I call to customer care i went to airtel store same probleam and no solution for this please help me on that.