Indian Oil Corporation [IOC] — excess of refill payment

Address:	Madurai, Tamil Nadu, 625532
Website:	IOC

Dear sir/madam
I'm a customer of shri usha gas agency-usilampatti (Tk), madurai (Dt), tn.
I received a cylinder on[protected] and the bill amount is 692.5/-, but the actual amount for this month is 638.5/-
I have some questions for you...
1) whats the actual amount?
2) why they are collect excess amount from the customer?
3) otherwise i know, the agecies are delivered without charges to door step to the customer, then why they are collect excess amount?
I attached the bill copy for your refernce...
Curomer name-k. Veeranan
Customer number-04643
Agency code-133016