Shocking service from Safair customer services

Safair cancelled our flight (in advance) and put us on another flight almost 12 hours later, so I requested a refund as the times did not suit us. A month later, part of the refund was received and ive since phoned more than 10 times to find out where the rest of the money is and no one can help us. Im at my wits end and don't know how to get my money back, shocking service from them and no one prepared to help me get it sorted out!!! Will definitely think twice before booking tickets with them again!