Still paying for a phone I don't have

I'm still waiting for a phone which I took to Telkom 11 months ago. There have been change of management twice and any person I get there can't assist me. The problem is that I'm paying for that contract and apparently my phone was received but no one knows where my phone is. What should I so cause I can't even call their head office cause apparently they also can't call their head office. They only deal with them via email. I have now got into another contract cause Telkom is not honoring our contract and this is costing me my money to cover the gap left by Telkom . Please assist