Horrible Service!

I desperately need help. I bought a Hyundai Creta from Hyundai Bedfordview just over 3 months ago. The sales person's name is Peter. I told him after i took the car that the I cannot play music with the USB and I can't use the GPS on the car, and He admitted that He will come collect the car to fix since it has Warranty. It's been 3 months, He keeps promising to come collect the car, but has failed all the time. I have tried to get hold of his manager to no avail

I called him on Friday, the 27th July 2018 and He promised to come collect the car on Monday, today 09:00 since it is now also due for service. He didn't pitch, neither did He call. I don't know what to do now, such a bad service from Hyundai.