Flipkart - Non delivery of item

I ordered for purchase of one Laptop being Order No OD ****************** on **th July **** with exchange facility and accordingly, I had paid Rs *****/- online. The delivery boy while visited our residence I was not at home but my father who is a senior citizen was at home. The delivery boy checked the exchange item and talked over his mobile with somebody else. He informed that the laptop is ok but one screw is missing. When I returned home, I lodged a complaint to customer care and told them to cancel the order and refund my money back as there was no option of “Cancel” was available in apps during the material time. The customer care talked to me and sent me a message to wait up to **th July **** and further informed me that they are trying for delivery with an exchange facility. You will appreciate that on **th there was no offer available and early in the morning they sent me a message that your order has been cancelled and the money will be refunded within **th July ****.
a) If the exchange was not possible at your end, why the order was not cancelled immediately.
b) Why Option of “Cancel” was not available on **th July **** i.e on the day of delivery although the ordered item not delivered.
c) Why my money was held at your end without paying me accrued interest up to **th July ****? Was my money was held for investing otherwise at your end?
d) What is the cause of sending me a message to wait up to **th July for resolving the matter when there was no offer available?
e) Was it your venture to refrain me to order further during offer period?
f) Why a further message sent to me on **th July **** that the problem will be resolved within **rd July ****?
g) Why the amount has not yet been credited in the respective account.