ExperienceDays.co.za Issue A Voucher & Then After You Pay, Tell You That It Is Unavailable

I purchased a voucher from ExperienceDays.co.za which I then went to exchange and upgrade. I paid for the difference in price and redeemed the voucher as it is intended to be a gift.

Once I have paid and redeemed the voucher I receive an email to say that the experience is no longer available and I can either revert back to the previous voucher or have credit to use on another voucher. I exchanged the voucher as I am unable to use it which is why I exchanged it in the first place. I do not want credit as I cannot afford for them to keep my money and to go and pay for another gift.

The experience is still being advertised as being available on the website so how many people is it being sold to, taking their money and then telling them it is unavailable?? THIS IS UNACCEPTABLE