Airtel — airtel store rejected to take postpaid to prepaid conversion request

Address:

Manyatha Tech part, Nagawara, Outer ring road, 560045

Today i visited the airtel store in manyatha tech park, bangalore to convert my airtel from post paid to pre-paid. Executive there asked me to come back after this months bill is generated, they told me that they cannot take the request now and telling me the reason that their system is designed to to take the conversion request in the middle of the month. And the super responsible airtel store manager even argued with me saying their systems are design for their convenience not for customer service.