I booked flight tickets thru travelstart for SAA, they deducted my money close to R3341 and now they do not want to refund me even after i sent the Proof of payment that they took my money

I booked flight tickets thru travelstart for SAA, they deducted my money close to R3341 and now they do not want to refund me even after i sent the Proof of payment that they took my money. They are rude and of no assistance instead they insist i pay more than my flight tickets by adding 711.29 more. I am struggling to get my refund from them but they canceled my booking