need help in redeaming woohoo gc got from Kotak 811

i recieved 200 gc number and pin from kotak. they told to redeem at https://kotak.woo...in

but this address not shoing any amazon gc for amount 200, only available ate 100 , 250 gc.

when i tried tonbuy 250 gc from 200 code its hows insufficient balance error. not alloaing me to pay rest of amount.

also not allowing to add 2 gc of 100 as max limit is only one voucher .
pleaee help guys how to solve this.