Dissatisfied

I am very disappointed with Vodacom services as I bought humidifier when it was R 99 using my vodabucks and paid in R 49 difference. The order was cancelled.. bucks returned to me however my money was never refunded. It has been over a year and when I ask for my money back they tell me to send POP. I have proof of purchase from app .Where am I going to get that when it has been over a year. I want my money back and I am ready to port my number