Security not reflect in my postpaid bill

Dear Sir,

This is to inform you that Bharti Airtel Ltd. company doing fraud for a customer.
when i was bought a new postpaid connection i had deposite Rs.250 as a refundable
amount for security His Sales Executive says me that 250rs is refundable but at this i want to change my network and closed my account in airtel thereafter he say that Rs.250 is activation charge not a security.

So, I request to you please take a action on this matter as soon as possible.

Thanks & Regards
Arshad Alvi