Best option is to buy gift cards with smart buy through payzapp and here you will get 5% cash back also. But for the purchase of Amazon shopping voucher, Amazon pay, Flipkart gift cards, we can't use wallet balance.
And you can pay for recharge/bill payment in payzapp itself using wallet balance and will get 5% cash points by applying promo code.
One more option is you can use payzapp card for recharge/ bill payment in Bajaj FinserV app at no extra cost. Some times there will be flash sale kind of offer, there you will get 10-20% discount/cash back offer for certain time.