Replacing a cranksensor on a Bmw320d nearly caused my starter to burn out and damaged it.Please read

Poor service.I hadvto replace my crankshaftcentre on my bmw as my wife broke down in Atterbury.I got a qoute from Michanic and they sent out Katlego to the job.I was quoted for an hour and a half to install the new part and to finalize the job.Howver it nearly took 3hours to complete as it is very difficult to replace working from the top and Katlego has stitches in his index finger wich made the task time consuming.In the process the starter red wire was loosened in order to fit the crank sensor.On arriving at the Car as i was checking in and out on the job.He was just finishing.He then asked his helper to put the jumper leads on and as soon as they connected the starter started cranking without using the ignition.The vehicle was put off and then he loosened one of the nuts on the shockabsorber mounting.This was strange and i asked why and he said that he used that nut to try and secure the red terminal wire on the starter but it was to wide and making a short and changed them back.this was very strange to me.They then finished the work as the car did not want to start as the battery was flat. i left with a uber and took the battery with me and fully charged it and returned the next morning to the car.On arrival i phoned Katlego and asked him if i could connect as i was concerned that the starter would start cranking by itself again as the previous day because of the wide nut that was used to tighten the red wire to the terminal.He assured me that this would not be the case and i connected the terminal pushed the starter button and drove home .The car did not want to go more than 80 and there were billows of black smoke coming out the exhaust.I stopped to check but could not see anything.On arrival at home i opened the bonnet again and saw that the airthrottlebody intake pipe was not clipped back and pushed it back and problem was solved the car was then parked.The car was parked and in the morning my wife started the car after pushing the starter button it cranked but car did not start in stead it kept on cranking and cranking .Even after pushing the start button to stop it it carried on at that time she honked and i came out running from the house wondering why she would not turn off the ignition and keep on cranking the motor while it didnt want to start.By the time i reached the car and tried to disconnect the battery terminal it finally stopped the battery drained after the continues crankin.I was so upset and phoned michanic and informed them what took place the day of repair and even that my car did not want to go and the black smoke i saw.I contacted the person that helped my wife next to the road and he loosend the intake as it seemed that the vehicle was fuel starved.Katlego was informed of the problem and he came out to my premises.Instead of looking again to see what the fault was it was decided it was a wear and tear issue.And after beeing told that it was not his fault and trying to start the vehicle again now staring with a terrible enjin noise a other mechanical person locally at my premises arrived at the scene and said that the bendix was not working because of the long cranking.I felt that the reason for the problem was a short on the starter as something was not put back right as it started after Katlego connected the starter positive side again.He said it just happened that the starter wore out because of the age i didnt agree as to the fact that a othe nut was used and the problem it gave previously when he tried to start the car after inserting the new crank sensor.They then after a short discussion left the premises with no help to look what the problem could be.So this morning i took the key and turned the ignition on pushed the ignition button and presto it started.i then did a excersice turned the car off completely fiddled with the red wire that goes to the starter and all of a sudden it started to crank again without stopping confirming my suspision that now there was a short on the terminal causing thi cranked again untill i disconnected the battery.I then sent my findings via whatsapp to him but no reply.So one problem solved and now we have a serious problem.I also tried phoning Michanic today but no reply.This leaves me no alternative as to get another mechanic out here to come and look at the connection on the starter wich i feel is the cause that started this not only is my new battery run down now but now the bendix or starter damaged.I now wonder why another nut was used and not the original put back firstly i cannot help to think that the mechanic damaged itbor cross threaded it while putting the red wire back hence he tried using the nut from the shock absober mounting.so now without a car and more costs involved after paying R2000 +