Multiply wallet

On 21 May I tried to make a purchase through the Multiply Online Shop. The totl price was R1074. I tried to make the purchase using the balance in my Multiply payment wallet (which was R831), and then by paying the balance with my credit card. Unfortunately (my mistake) I entered a wrong detail for the credit card, so the transaction never went through (i.e. the purchase wasn't made). Nevertheless, the amount of R831 was deducted from my Multiply payment wallet. Some days later an amount of R331 was refunded into my payment wallet, but the balance of R500 has never been returned. I have no idea why. I have now written no less than eight emails to Momentum (multiplyonlineshop.co.za) to try and sort the matter out. At least two of these did not even receive the courtesy of a response. On other occasions I was told things like "the matter is currently under investigation", or "the matter has been referred to our technical team." The latest email contained a "sincere apology" but no resolution - that was on 16 July and I've heard nothing since. This is simply unacceptable. It is not a difficult matter to sort out, and can be easily resolved by comparing the payments made from my Multiply wallet against purchases made from the Multiply online shop. Perhaps they are simply hoping I will go away. Either way, I am disappointed as our experience with Momentum has generally been good. It is very poor customer service.