The worst customer service ever!

I bought a Hyundai i120 demo vehicle from Hyundai East London, at the end of March 2020 just before lockdown started. In the first week when i got the car, i heard a humming sound coming from the car. I told the sales person about it. He then told me that they are closed due to lockdown. The car went in for a service on the 18th of June 2020, they then told me that the car needs to come back because they need to fix the gearbox (where the sound came from). I took the car back on the 25th of June, where they then told me that it would take more or less two days to be fixed. On the 30th of June (5 days later) i contacted the sales person to find out how far they are with the car because no one informed me about anything. They couldn’t tell me when it would be fixed. On the 3rd of July they gave me a courtesy car. On the 8th of July i had to contact them again trying to find out when they would be done because no one has informed me as to how far they are with the car. On the 11th of July they told me that the parts arrived and will be assembled during that week. On the 16th of July i had to contact them again, they then told me that they ordered the wrong parts and have to order new parts again, they promised to let me know when it arrives and when it will be done. On the 24th of July , still no one informed me about anything. I called them and they told me that they put the parts in but the car is still making the same sound, they would get back to me. On the 29th of July, still no one has called me. I had to call them, they then told me that they had to strip the gearbox again and order parts again which will arrive on Friday then they will let me know. My car has been in the workshop for more than a month however i am still paying for it. I am utterly disappointed by the poor service rendered by Hyundai East London. I would like to know why Hyundai sold me a faulty car?