I need help what can I do to resolve this

Hello!!Is Mmatau here I had a problem with a car on the 20 May 2018 so on the second I took it to Diatech,which they advise me to get a new engine as they said is gonna be costly to fix it,as I left the car at their place from 22 May till I got the engine on the 27 September at Bishops which was collected by Diatech..I was told that I will get my car after 5 days and days went by I had to call was told that will get a car next week which was first week October and it never happened...When I called to check when am I receiving a car was told that they had a problem with gearbox and when I took the car to them it was drivable and all gears went on gears so they kept on giving me different stories every week and when I told them that the Garranty of Thebes engine is ending then they rush and the car was showing signs of pressure oil and they now said is not their fault they have to return it where I bought it,,I had to negotiate with Bishops autospares where I bought engine which they said I have to bring the car to them then they can see what’s wrong,,,I did that I send the car with towing truck had to pay it Diatech didn’t help me on it hence they said they had to pay 15 000 to replace a part on gearbox that one of their stuff members broke it...so when I got to Bishop they discovered that the are things that need to be fixed which my mechanic didn’t fix them wires not being connected I was charged R650 I had to pay it as well including the towing money R2800,.so I told them that they don’t deal with gearbox they have to take it elsewhere to fix it and they don’t wanna do It every week they take the gearbox in and out of the car I don’t know what to do I need help on this,,,I spoke to them o. This Friday 16 Nov they told me they took it off gearbox and put different one but still the car doesn’t go smoothly from gear 4 till 7 ...am stuck I need a car they volunteered to give me their bakkie that came with lots of terms which I didn’t agree with to take it worse even the kilos wasn’t supposed to travel over 200km but they not helping me with my car is now 3 months and I have been renting a car which cost me a lot and I have to go for holidays I can’t do things even to work I struggle I need help