Time wasters

I went to Lewis to purchase couches on my account and was advised I qualify for the cashback option. Upon arrival I chose my lounge suite and a freezer. After about an hour and a half the salesman goes to print my contract only to advise me the lounge suite isn't available on cashback I must choose another one. After choosing another one he again returns after 10 mins to say there is no more cashback. Why did I go through all the trouble of picking specific couches, waiting for the thing to approve and everything only to be told it has been expired. It was such a waste of my time and made me late for an appointment. If I had known I could've picked something else that I would've preferred to the lounge suite that was on cashback. To top it off the manager doesn't even bother to come and apologise on the store's behalf.