Amazon India - cashback denied

Hi, I ordered a Lenovo **.*" Professional Backpack on **th Mar'** for Rs ****. In the rewards section, Amazon was showing an offer that said that if I order any luggage before **st Mar'** I will get back **% cashback up to Rs. ***. And so I decided to order. Post delivery I did not receive the cash back as mentioned in T&C. So I contacted their customer care which said that I am entitled to the cashback and my case will be addressed in the next * working days. Despite ** days from order/delivery no one replied nor did I get cashback. So on *th April I decided to follow up with their customer care once again. After spending roughly *hr+ chasing the customer care team on chatbot/phone etc. I received an email that the concerned order does not fall in the luggage category and instead it is a computer accessory. The reason I am aggrieved is that it is common sense that any bag is bound to fall in the luggage category. Neither was there any specific exclusion mentioned for Lenovo backpacks or for that matter any particular backpack. In fact their T&C says that "This Offer is applicable on all bags, backpacks, wallets & luggage. Not valid on handbags." Still I am getting denied the cashback.