Paytm — Over charged from my account.

I have recharged my Delhi Metro card on 13.06.2016 for Rupees 500/-. As per your discount 4% ie Rupees Rs. 20/- to be credited in my pay TM credit account. You have deducted rupees 490/- from my account instead of Rs. 480/- ie Rs. 10/- extra. Why.?Refund the extra money to my account.
Card no. [protected].

Regards,

P.MAHENDRA,
email: p.[protected]@gmail.com
Mbl: [protected]