Orra Diamond Jewellery — monthly instalment scheme

Hi,
I am orra customer and invested in monthly scheme since last 10 months. This month i. E on 5th of nov. 2018, when i went to orra store at db mall, bhopal to purchase my diamond product, they refused to give me diwali offer of 20% discount on diamond jewellery. 60k was my investment+ 9000 was orra's share. The mrp of my product was 88000. After discount (- 20%) the price was around 70, 400. But they ask me to pay 19000 rs. As difference of my invested money + their share.
So, my question to orra is - what is the benefit of investing my money to your company?? If i am not eligible for your company's festival offers. To whom you are giving this discount?? Is there any difference between your regular or instant customer. My money is still with them, either give me 20% discount or give my money back with interest. It would be better if i had invested my money in bank (Rd) and with that money i could enjoy your festival discount.