Poor Service Delivery

My dad recently purchased a Tuscon N series for me, at Hyundai Umhlanga, the deal was signed and a R300 000 deposit was paid to Hyundai, the salesperson was content and said that the vehicle was ordered and we should receive it by the 20th of December. A week later he calls to say that he can only get the vehicle in 2018 and it will cost more so he wants to deposit the R300 000 back into my dads account. They are basically asking him to pay R60 000 more after the deal has already been signed. What kind of joke is this? I chose Hyundai thinking that it was a reputable brand however this is not acceptable. Please advise me as to what will be done or will have to contact my lawyer. My name is Charleen Reddy and my contact number is ********** 073. Your help will be highly appreciated.