Old mutual refuses to refund me

I opened an investment account at old mutual, I was paying a lot into my investment account. I then wanted to cancel it which I did and now they are failing to give back my money. Olwethu was the lady that was assisting and everytime I asked for my money she would ask me for my bank statement and never does anything about it. I have been waiting for months now. I truly appalled by the service I've received. I am not the only person that has an issue, a lot of us at work have been complaining.