It was them not being good customer service, the general rule in customer service is basically try and do what ever the customer wants. In this case they wanted a coupon (probably for 10-20% off extremely expensive lamps) after buying a $2000 mattress. This doesn't matter and should have been given immediately.
The positive review of a single person is more important then losing 10-20% on a sale after a user already purchased another product.
Due to them not giving them a 10-20% coupon they lost a $2000 mattress sale and got a bad review on a site.