Grofers — Fooling people on the name of guaranteed inaam

Grofers introduced sale scheme that on every purchase of 1800 inr, there is a guaranteed inaam and i choose one of the gift but when i receive order, they said my choosen guaranteed gift is out of stock.
They do not know the meaning of guaranteed.
Also, not sending my order on time. Customer service is really worst. They do not reply on time.
Secondly they mentioned a scheme that on 1st order when user sign up with someone's referral code, they gift one gift free but in their app, gift section is empty. User cannot see or select any item. They are just fooling people.