No communication and stalling to cancel upgrade

Did an upgrade deal with Mondo/MTN on 29 October. After 2 hours I realized this deal is not what I needed, so I phoned Mondo to cancel. The lady said it will take approximately 3 to 5 working days. Well, I'm still waiting for the cancellation to go through. In the meantime nobody answers their phones and even the chatbot say you are outside working hours 10 in the morning!