Duroflex — Unable to exchange matteress as agreed while buying it

I bought 2 single and 1 king size mattress from duroflex showroom. During the purchase sales executive said we can exchange it in 2 days if we didn't like it. But later they reducing it to for exchange.
The mattress height is not suitable for my cot. In the showroom, they have showcased 8inches mattress majorly and mentioned that that's new topping to improve the experience. But 8inch is not suitable for our cot and reported for exchange as soon as we got the mattress. But company is pointing some website about return and refund policy and refusing to exchange.