Quote provided stating stock is available! Money spent on a voucher and apparently no stock!

I called Tiger Wheel and Tyre in Parklands (Sandown) to enquire about a tyre 225 45 19. The gentleman I spoke to on the phone informed me that they had a tyre available (Han****) for R2499, and I then informed him that I would be coming in to purchase the tyre at around 3pm. I arrived at the workshop, and the supervisor/manager informed me that the guy had already left, and that there was no tyre for R2499. I then enquired what prices they had, and he informed me that the cheapest brand was Continental for R4200. This is very upsetting for because I spent money purchasing a R2500 Tigerwheel and Tyre voucher which I am now stuck with?... It is false advertising and amounts to utter waste of my time, energy and let alone money!!! Utterly unacceptable!!!!