Incorrect/ Unauthorised debit order

During November and December i had debit order of R99.00 (R198) from the company called Greystone. i phoned the number that appear on the statement but advised that they process debit order on behalf of the companies and provided me number 0315001230 to lodge a dispute as this was not authorised by me. I have done all the conducts since 06 Jan 2015 until today i don't get any positive feedback from Greystone. Everytime when i phone they take down my number and promise to phone me back but never done that. Recently i phoned the same number that appear on my statement 0126539100 now they refer me to 012 140 0126 and said they don't deal with Greystone anymore. I phone 012 1400126 to find out they promised to lodge a dispute and advise me today nothing happened and when you phone they keep on asking reference number but nothing happen. How do i go aout this as my spending on call is now almost 1 debit order. I really want my money back. They take long on the phone and make sure that if you use airtime its get finished before you get help. I went back and phone Greystone but the number is either engaged or ringing forever or someone will pick up and ask you to phone later.