Wrong fuel put in my car causing engine damage and garage refuse to take responsibility

On the 29th of August 2020 just before 06h00 in the morning,I went to go out in petrol in my car,that was R200.After the petrol attendant put in petrol,I drove off, less then a kilometre from the garage,my car had some kind of mechanical problem.I had to force my car to a safe area due to the fact that it was a bit dangerous to leave my car in that vicinity of Salt lake in Port Elizabeth.I managed to get my car to a friend's house.On checking the car at a later stage,it was discovered that the petrol attendant has put diesel in my car,instead of petrol.I went back to the garage with the petrol slip which stated that the attendant did indeed put diesel in my car.My engine had a serious noice after the diesel was drained.I reported it to the manager of the garage,he insisted that diesel would never damage a petrol engin.He told me to bring the car so that they can sort it out,the car was towed to guy that they referred to as a "qualified mechanic.A few days later my car was standing at the garage,the same Engen garage n West End,Port Elizabeth that put diesel in my car..I wasn't even contacted to say that my car was parked at the garage.I went to the manager to find out if it was sorted out,that's when the manager and the garage owner,Mr Allie argued with me and insisted that diesel would never damage a petrol engine and that diesel would instead clean a petrol engine.I left the car there and a few weeks after that,I went to go fetch the keys and tow it home,only to find out that they couldn't find my car keys,the manager by the name of Guest lost my car keys,which included my headlock key,my home door latch key,the gate key,and my car alarm immobilizer (remote)..The manager was so arrogant that he refused to take responsibility for the keys,refuse to replace my alarm immobilizer.Thevissue have up until today not been sorted,my car is still not fixed and my keys is still missing and I can't activate the alarm of my car..I was treated with disrespect and humiliated by the garage owner and the garage manager.The problem could have been sorted quickly and efficiently because the garage owner,Mr Allie has a spares shop where he sells motor vehicle spares and part,brand new,but instead they told me that it's just a coincidence that my car broke there after putting diesel in my car.,a Toyota Corolla 1.3.