Hyundai Springfield - Worst Service

HI All, i trust you are well.

i was recently a victim of car theft which has me searching for a new vehicle. Upon visiting Hyundai Springfield Park on 17/11/2017 i noticed a VW Polo for sale in the lot. The salesman informed me that it was a trade in and i told him i was willing to purchase. The vehicle had a few defects which i asked him to address and upon concurring with the used sales manager, he agreed. I wished to finance the vehicle and the necessary forms were signed immediately at the dealership. i did not have other documentation on my person. All these were submitted via email that same day all before 3 pm. The FNI then contacted me on monday 20/11/2017, to discuss a rate the bank had offered which i said i was unhappy with and she must review as i had received a better rate from other dealerships. No OTP was sent to me to sign at any point in time however all finance was approved. The salesman has been evasive since the 18/11/2017 and i finally managed to get through to him today, 21/11/2017. He now informs me that car has already been sold. i have closed other finance deals for vehicles because such was my intent on purchasing this vehicle. Now i am without a vehicle and my search starts again from step one. i called the dealer principle who tells me that they work on the "first come first served basis" which i find hypocritical as my application was first on that vehicle as it had just come in before i arrived. he had informed me that during the time taken to review my bank offered interest rate, a customer who had accepted all terms and conditions concluded the deal and the car is now theirs. i would like to know if this is an ethical way of doing business as the review of offered interest rate is not within my power. I would also like to point out that at no time was i informed that the vehicle had been sold already. i, as the customer, had to call the dealership to find this out.