Cannot leave a 30 day rolling contract

Joined on a 30 day rolling month to month data sim contract so that I could leave when required. Since November I have been trying to cancel. I go into the store to be told that I am on a 2 year contract and must pay an exit fee to leave. This is not true and they cannot prove it. I asked for the contract signed but they could not provide it either. What's more - I had to pay a R 700 deposit of which I was told I could get back after a few months. They won't return it until the end of this fantasy 2 year contract. The 2 year contract came with a free router. I did not receive or want a router as I joined on a monthly 30 rolling contract. Yet more proof that Telkom is at fault for entering me incorrectly in their system. If they make me stay for two years they owe me a router on top. That being said i don't want a router I want to LEAVE and receive my deposit. Terrible experience. Thank you.