Punjab State Power Corporation [PSPCL] — bill generation

Address: Ludhiana, Punjab, 141001

Consumer no. [protected]
Bill generated in the email with atttachment which came is 3990 and when you try to pay online on the pspcl website, it comes as 4390. Why there is discrepancy of 400 rs? There is no pending amount of earlier bill, still i am not able to pay 3990 which is the actual amount generated. Why am i getting charged 400rs extra. Please take an action