Delhi Metro Rail Corporation [Dmrc] — inappropriate value addition in smart card

Last evening i got a new smart card from patel chowk customer service centre (50+450).450 was d amount to be dre in the smart card and 50rs. For issuing the card. I swiped at the entry point and to my surprise the card balance shown was 406rs. I contacted the staff who issued me the metro card and enquired about the less balance in card viz it should have been 450 rs. Although he issued me a new card with 450rs. As card balance and said the earlier card was just lying over here and i gave t to u by mistake.
Request the authorities to look into the matter and find out whether it was a genuine mistake or an intentional one. So that such things can be taken care of in d future.