Unjust and unfair treatment

On 25th April 2016 I came across a Toyota Corolla which was advertised on Mccarthy Toyota Midrand's Official website. On 26th April 2016 I enquired about the vehicle from the dealer directly. I was assisted by Petrus who informed me that the vehicle was available at the advertised price. Later that day i went to inspect the vehicle and if satisfied with the condition of the vehicle, conclude the transaction. Once I was satisfied with the vehicle i was asked by Petrus to sign an Offer to Purchase. After having signed the offer to purchase and submitting it, Petrus introduced me to a man by the name of Danie Strydom ( the F&I Business Manager) who requested that i pay a deposit of R5000.00. Mr Strydom advised further that if i pay the outstanding balance on Thursday, the vehicle can be collected on Friday. Mr Strydom sent me an email requesting that i CC all the recipients in the email my proof of payment which i duly did. He rep**** in writing and advised as follows "this is perfect, the car is secured for you". At this point it was clear that the sale was finalized, the deposit having been paid and the balance tendered. After the conclusion of the sale, a day later i was contacted by Petrus and the dealer Principal Albert who informed me that the car was sold to me at a lower price and therefore there was no conclusion of the sale as they claim that the contract between us was not binding as it was not accepted by a duly authorised agent of McCarthy. They acknowledge that Mr Strydom being a business Manager was duly authorised but deny that he accepted the offer. It is sad that they have no regard for the law as well as for their customers. Even though the sale is binding they refuse to release the vehicle at the price agreed. I am deeply disappointed by their attitudes as well as their customer service.