Mechanical problems

I bought a Renault sandero 900T Stepway at Bethlehem franchise in 2016-02-04. Two weeks after the sale i started hearing a knocking sound coming from the front wheels. I took the car back to the dealer and informed them that there is a knocking coming from the front wheels. It was taken in for repairs. On the same after the released the car the knocking sound was still there. I took the car back after for couple of times still the car is not fixed. I went again this year this week on monday with the same problem but i was told that the will arrange with the technician to see my car but still no call. The engine also shuts down when traveling below 2000 refs this has also been thre same as the knocking sound. Lastly. When i bought a car i was given the spare key because they claimed that the previous owner said will bring it. Its almost a year struggling to get help from Renault. I even sent an email to their head office it seems to me they are waiting the for the car to breakdown with me the road so that they can wash their hands and leave me there. If i knew that this was the kind of service i will be getting i would have never done business with Renault. It seems to me the do not care about customers. Once u sign on the dotted line and the bank pays them, then they forget who you are. Please if anyone from Renault is reading this. Help me with the bad service i have been receiving until now.