Airtel — airtel employees exploiting new subscribers

Address:

560015

Dear sir,
I have visited airtel office near jalahalli cross, bangalore-57 for porting my mobile number to airtel because of low signal problem. But the person in their office refused to port the number unless i am ready to pay a total of rs.520/- for 3 months data pack. I need only talk time pack not data, but he was not ready to port the number for anything less than rs.520/-. Now i am going to any other providers which has better signal in my house. Why airtel allowed their employees to exploit the poor customers like this? Is it really legal?
Regards
Prakash