Ordered stock comes in more expensive

In mid-December 2014, I went to Mr Price Sport Hemmingways to purchase an exercise bench. The floor unit of the Maxed elite bench was damaged so I asked the assistant to order another & was told that it could take some time to arrive. I was also assured that the current price would be valid once the item arrived & was given a slip with the order details & price. The item finally arrived & we went to collect it but I was overcharged by R600. When my wife queried the price, the assistant confirmed the lower price of R2999 but couldn't do a reversal over the weekend & indicated that we would have to return on Monday. I returned to Mr Price Sport today (23/02), only to be told that the higher price would remain as the order had taken longer than two weeks. The only option I now have is to pay the higher price or return the item. This policy should've been made clear last year & I would not have wasted my time. It is now over two months & the item has to be returned because Mr Price Sport took too long to bring the item down. I will return my entire R6578 purchase from Saturday because I would prefer not to do business with a company who reneges on assurances made to the customer.