Upgraded contract, now nothing is working

Upgraded one of my Telkom mobile contracts via this company. New phone and SIM card was delivered. On the same day my existing SIM stopped working and the new one does not appear to be activated. Called Telkom and they have no knowledge of the new SIM. Tried unsuccessfully throughout the entire day to contact Sell direct on *** and ***, but they seem not to be interested in answering their phones. Wish I had checked here before dealing with them, This is pathetic/