Billed for an inactive device

I took a 150MB WiFi contract with Telkom in the end of November through their outbound Sales Department after they called me to sell me the product. The device was delivered in the first week of (6 or 7) December. I opened the delivery box that had the device box inside to check if the device was sealed. I only opened the device that weekend, only to find that there was no sim card included. I've been calling Telkom customer service from the 14th December requesting them to send me the sim card,\. I was told my card will be delivered to be in 24 to 48 hours. I went through to their website and tried to chat to the "Talk to us" team. I was told the sim card is active and was used on the 21st December. When I asked who used it or for what it was used for, I was cut off. Please help. I've been holding for their Sales department for the past 45 minutes and there is no answe.