Very odd and unruly sales person

I have to say that i found the service i received from Tile Africa greenstone rather, after over 3 years of excellent service (and over 10 sales), i cant really comprehend why we were given such poor.

Just as we are about to leave the store, we are approached by one of the staff members who advises that they have a clearance on some of the stock and he advises to take a look. we go back in the store and have a look and after a short while we decide to make a purchase on one of the items in the amount of about 3.5K.

as we are about to make a payment, the sales person advises that we need to pay 5.6K, to our suprise we tell him that this is not the price we were expecting to pay as the items price was clearly marked, he then proceeds to take off the price tags off the items, and then suddenly tells us that the price we had seen and read were incorrect, that as it may, he then proceeds to say to us that there are no claims we make to prove that the price was as we read it, and since there was no discounted amount displayed on the price we cannot also claim for the discount. and thus, its either we pay the 5.6K or there will be no sale... now as we request that he calls the gentleman who introduced us to the sale, he tells us that this person has no jurisdiction over him so there's nothing we can do to change the outcome of the enquiry. I would rather not give out any names on this platform, but i found the gentleman to be very rude and *****. Like I say I have frequently done business with greenstone and received world class service, I just don't understand what happened today