Airtel Digital Tv - Mental Harrsement by airtel

Dear Airtel team,

I have been associated with Airtel for more than ** years( Customer ID: **********).

I'm having an Airtel Internet STB. Morning i received a call from the Airtel service center (ACE Associate - Madhavaram, Chennai - Manager name - Durai).
they said that there was a free upgrade( No additional charges) available after changing it to Xstream box .After * hours they are calling and informing that **** INR will be debited in my post paid bill.

then i asked why they said that " if you don't want we will collect and will give you your old box"
this affected me both mentally and physically( waited for more than * hrs for installation & * Hrs for activation) . Is this the way to treat customers ?
if i buy a product and return after * hours will airtel agree and refund the amount to me?
I needed an action against the service provider( ACE - Associate location : Madhavaram, Chennai)
and as per promise they made I required an Xstream box without any additional charges