Poor Customer Service

I went to buy a Lap Top at Makro today and found Acer on promotion to go with a home office package. The sales consultant found that there was no more stock of the product except the one on display. When I indicated a lack of interest in buying something that has been on the display desk, the sales agent called the manager or supervisor and they agreed to give me a discount on it. At the till point, the cashier and sales consultant battled to put the transaction through. I was then told that I needed to pay the full amount as the product was on promotion already. When I raised and objection to something that was already promised and agreed, the sales consultant called the manager who sated that I will be given a discount when I went to Makro next time. All that was unfortunately word of mouth. I was not happy with that and asked to see the manager. The sales consultant called the manager and I had to wait for more than 30 minutes for him. I was told that the manager was busy with another customer. I waited and ultimately the manager, Mr Shonald Sono arrived. After I had relayed the whole incident again, he confirmed that I will be given a discount to be determined by himself when I went to buy at Makro next time. It was again on a work of mouth and on the basis that I have to trust him - even though I did not know him. I finally had to leave the store after paying the full price and with a product that was opened and on the display table.