Terrible experience once again

Purchased a replacement Dstv explora decoder 3a for R699 as they were clearing stock for the new once to come in which is the 3b. The purchase was done Monday evening. This morning I got a call from menlyn branch advising me that they no longer have stock and this must have been a mistake. Now only new once are available. I check on the online store and noticed that the 3b are on special for the same price R699. Now I get told I have to wait for a refund on the current purchase then need to make a new purchase. I don't understand why I should be inconvenienced due to the store's fault. I mean why can they send me the new decoder since the price is the same. They can always substitute the two sales as as business decision. I am not a happy client at all. Order no ***