Disappointing Sorbet Facial Experience.

I booked the Environ Youth reset facial. The facial was awesome. But I was overcharged and they didn't have the DF machine either. As soon as I arrived, I was informed they didn't have the machine, so I was fine with that. But when I went to pay, after using a R500 voucher, I was still charged an additional R490. The facial is R850. I'm just annoyed I was overcharged. I mean, who does that? It's incredibly unprofessional. I sent a message to them. They apologised and said someone from the Fourways Branch would contact me. It's been 4 days.