Bad workmanship

Took my car in for a water and oil leak and to replace cv joint. When I got under the car a while later after a dealership told me that they will not work on the car because of what was done on the car at Car service and repair centre Pretoria North. The water pipe that was "replace" on the car was packed with silicone around it. The gear link was tied up with a cabletie. Oil leak was still there. When I went to Car service and repair centre the owner told me they will take the silicone off and then I can tell the mechanic how much silicone to put on. When I asked him how do I know the pipe was replaced because I never received any old parts back? He showed me invoices that the parts was bought. And then I asked how can I be sure that it was fitted because of all the silicone on the pipe he said I can take his word. Then I asked who and why they tied the gear link with a cable tie he said how can I proof it was them and not me. He got aggressive and said I should bring my car and they will take the silicone off ad I should leave. The owner himself doesn't know how to service a car or what should be done on a car. How can you run a bussiness and not know what your workers do and how they should do it? Realy bad service and customer service. Never take your car to them!!!