worst service

On the 27th of December I took my car in for a service, it was at 160000 km. I told them I know its not due till 165 000 km but when I brake the car makes a squeaky sound, it uses too much petrol and it does not have power. I was called and informed that the reason is because 3 of my coils are damaged, and the brake pads need to be replaced. I told them to please replace the brake pads but leave the coils for now as I could not afford them because they insisted I change all four. When I went to collect my car it was still making the squeaky sound so they quickly fixed it while I waited. Driving off I was not satisfied because my car was in the same state I brought it in. I googled and found that the air filter, coils, spark plugs are all things that affect power and fuel consumption so I took my car to another mechanic for a second opinion and he confirmed Hyundai did not do what was supposed to be done. Brake pads had been changed but not brake plates, the person who tried cleaning the air filter tore it and put it back hoping I would not notice,only one of the coils was damaged other wise the car would not have moved had it been 3 like they said, the spark plugs where not changed and a few other technical things he found along the way. I then contacted Ian the manager and told him I would like to log a formal complaint and he did not take responsibility instead told me that they serviced the car according to manufacture specifications. I informed him the reason I bought the car in was 3 problems I had and he did nothing to sort out those problems what is more important, fixing what needs to be fixed or fixing according to manufacture specifications and risking my engine being damaged? the manager told me after I had said no to coils and asked for a printed quote so I can budget they then included spark plug,I said not only did you not specifically address spark plugs but when you were fixing the car had you given me the option to have them replaced I would gave given the go ahead because that I could afford the only thing I could not afford was R8000 for the coils, He just apologized about the air filter and addressed my complaint as an issue that just needed explanation. I am worried and feel like they took advantage of the fact that I do not know any thing regarding mechanic and took my money without helping me. I would like to know how it is that you as an organisation can help me in a matter like this because Hyundai has put me in a financial detriment and caused me distress.