Levi's India — regarding extra money charged

This is reference to my order no. [protected]. As per the offer of buy 2 get 2 free, we got 8 jeans from elante mall, chandigarh. But we were charged rs. 600 extra for the same. As i am attaching the picture of my bill, you can see that with the billing of first two jeans, the next two were free and same as with the next four. The total amount comes out to be rs. 13596. But they charged us rs. 14196. Kindly refund us rs. 600 we paid over and above. This is highly unprofessional and cannot be expected from such an esteemed company. Kindly look into this matter and reply soon otherwise we have to approach consumer forum.
I am a levi's member sukhamrit with my account registered on phone number [protected]