Do not honour prices as on their display's

I went to House and Home Retail Park to look at a docking station for my tablet they had 2 that had my interest both marked at the price of R399.20. I was keen on purchasing the one model unfortunately they only had the display demo in stock without its box or manual they only had the remote. I then phoned the Parklands Branch and spoke to a salesman who had one in stock with its box and accessories however their price for the item was R799.00 he assured me that if I bring him proof of the price his manager would match the price of the other branch. When visiting the other branch the manger refused to match the price and explained to me that the other price was due to the fact that item had been discontinued and was being phased out and due to the item being incomplete (No box or manual). I then returned the following day to the original branch to complete the purchase of the cheaper demo unit only to find that the price had now been altered to R799.00. I took this matter up with the branch manager who then, after me showing him the picture I took of the item, contacted his regional manager who then refused to honour the price I saw as they were not certain about my integrity.