Money not refunded

I paid for two tickets for Freedom Fest SA's Pretoria show. The organisers cancelled the show and promised to pay back our ticket money by the 18 May 2015. The show was supposed to happen on the 25 April 2015 at SuperSport Park in Centurion, but I was cancelled the previous week. Our money still have not been repaid as of the 20 May 2015. This is absolutely ridiculous that they are not paying back our money and something should be done about this matter.