Totally misinformed

I was visiting Qwantani Resort this past weekend and decided to make use of the Cell-U beauty spa on site. I booked and paid for a treatment for myself and my husband. My husband decided he didn't want the 3 hour treatment that I had paid for and asked if he could change it for an hour treatment. I contacted the spa and explained the situation and was told that it was not a problem at all, there would be a credit of R600 due to me which they will refund to my account by that afternoon provided that I left my account details...which I did. I left to return to Johannesburg that afternoon. Today I have been contacted by Cell -U beauty spas regional office only you be told that their policy stipulates that the amount owed to me must be forfeited but they have made a concession by issuing a voucher to the value of R600 which can be redeemed at any of their spas. None of which by the way was explained to me or raised while I was physically at the spa. I was promised that the amounts owed owed to me would be returned to my account and now 24 hours later I am told a completely different story. Surely companies should not be allowed to misinform customers like this? Really annoyed at this