Airtel — Data voucher redeemed and reflecting but I can't use it because I don't have an active data plan on Airtel

Address:	Airtel Center, Plot No. 16, Udyog Vihar Phase IV, Gurgaon- 122015
Website:	www.airtel.in

Data voucher redeemed and reflecting but i cant use it because i don't have active data plan, so i tried to contact support and guess what i cant even contact them because i don't have an active plan on my prepaid number (i thought this problem is insufficient/ignisufficient but wait, it's wrong ) why i could redeem the coupon at all in the first place if i don't have an active plan ? so it could be wasted ? or i must recharge my number to use that 1gb data that is showing 2 days validity limit by adding a 500 rupees worth plan do i can use "1 GB" data?
its a complete scam isn't it ?