Over changed VAT with no response!

????My company made a booking from Nelspruit to Cape Town. When we received the invoice for the booking, we realized that the VAT that was changed was more than it should've been. I called Travel Start on the 29/05/2019. enquiring the VAT that was over-charged. the first time I spoke to Miguel. We requested that they get back to us with an answer before Friday 31/05/2019. Empty promises where made. Friday came still no answer from travel start. I called again spoke to Miguel again. Monday 03/06/2019 I called again and spoke to a Fatima who made the same empty promises. (Keep in mind that I have recordings of all phone calls made). Finally, 10 June 2019 I asked to speak to a supervisor or manager when I called AGAIN- Dillion Mohamed who emailed me an invoice with the same figures nothing else. I mailed back to say that Travelstart has overcharged us VAT. it is now the 13th of June 2019. STILL NO ANSWER TO REPLY...NOTHING! Reference Number ZA ********** 2.