Cell Number Porting

I bought a mobile phone at telkom mobile and i asked them to port my old mtn number to their network so that i retain my number, which they did on monday the 16th November 2015. I was told the number will be successfully ported within 72hrs from that monday and that the old phone will not have a network once the porting is done. I started receiving calls on the new phone and i was convinced that the porting was successful until i got another call on the old phone with the same number ported to telkom. i still receive calls on the old & new phones and when i switch the old phone off off i am unavailable. i called telkom several times but their agents tell me i am active on their network and that there's nothing they can do because their system shows i am in their network and active. i am now active on 2 different networks with the same number and MTN says they can't just deactivate my number without Telkom's request to port my number, which is understandable to me. Telkom keeps saying they are investigating the matter and they call me back to say the matter has been resolved but the problem stays the same... Please assist me