PayTM - Issue of void cashback code by paytm

Purchased * products from Paytm using code BIJLIBILL*** & other promo codes in the month of April and May for which I have received coupons to redeem cashback assured against successful EB payment. Among these * codes, one code received against the purchase of Suzuki access scooter is usable once in a month valid till the month of December. Whereas the other five codes are valid for one-time use. I have redeemed * coupon (Suzuki access coupon) * coupons ( Suzuki access coupon and * another product's) and * coupons (Suzuki access coupon and * other product's coupon) in the month of April and May and June respectively. In this situation, I am left with two coupons worth *** Rs. Each which am not able to use as paytm restricts usage of two codes in a month (this was not mentioned in t&c at the time of purchase and was updated in Paytm only after I have raised the concern on June *rd, Paytm query reference no. ********). After I raised this concern to Paytm support, they have updated recently the t&c for the use of BIJLIBILL promo code and also they have upgraded from * promo codes to * codes in a month. I have requested them to revalidate the expiry date of the code issued or club as a single code, so it could be utilised next month. But Paytm continuously denies stating that it's "t&c implies only * EB codes in a month".
I have raised this issue with national consumer helpline too, but the reply of Paytm remains the same even to them. My concern is at the time of purchase I was not guided that only two codes could be used in a month, the code issued by Paytm against the two products were void. Under unfair trade practice, they have lured the consumer to buy more products hiding the limitations of t&c and later denying the assured cashback to the consumer.