Telkom does not care

I have taken out a WIFI contract from Telkom in October 2016. I was not advised that the unit is voice enabled and my primary reason was to have data access for my kids. Voice was enabled and the bill reached R3000. Telkom confirms that they are not held accountable. I believe the incorrect advise was given as if I was told I could have been able to make a more informed decision as to whether I should take the contract or not. Gateway branch and the manager cannot give me a copy of my contract and are extremely rude and don't care.