Wrong sparewheel.

On 22/05/2017 I bought an MERCEDES-BENZ C180 BE CLASSIC A/T from Hyundai Bellville. Purchase price R 235 256,95, the vehicle were finance trough Stannic. Acc. ********** 50001. On 11 Jan 2018 I went to Potchefstroom with this vehicle. Just outside Klersdorp the electronic onboard computer system shows me "CHECK WHEEL PRESSURE". I stopped at the next garage and check the 4 tires. One of them was almost flat, and I pumped it. While pumping the tire, I could hear the air is leaking out. After further investigation I found a 5mm slash on the side wall. I remove the spare from the boot, jacked the car up, take the damaged wheel off. Then to my greatest surprise!!! The spare wheel in my 2012 MERCEDES-BENZ C180 BE CLASSIC A/T, DOES NOT FIT ON MY CAR!!!! I had to walked to an 24hours tire repair stand on Klersdorp taxi rank. Luckily they could help me, and I was able to travel to Potch and back to Cape Town. On 16/01/2018 I went with my car to Hyundai Bellville. Show Mr. Ryan Steyn the predicament that I am in. He promised that they will sort this out ASAP. On 23/01/2018 I phoned Mr. Ryan Steyn, on which his reply was that his manager is not "IN" and he cannot made the call regarding my problem. He have to waite on his manager CARL. on 31/01/2018 I phoned him again. On which he rep**** to me the following: His manager cannot believe that Hyundai Bellville will sold me a 2012 MERCEDES-BENZ C180 BE CLASSIC A/T with the wrong spare wheel. And that I have bought the car to long ago, for Hyundai Bellville to replace my INCORRECT spare wheel. Sorry. I then threatened him with a law sue, which he said that is my right to do. WHO CAN HELP ME WITH THIS?