check engine light

I will never take my car to be serviced here again. I usually go to the Nissan on Ridge Pike but decided to go to Ardmore since it is closer to my job and they provide a shuttle service. The shuttle is the only good thing about the service department. And is not worth sacrificing the condition of my Car. I brought my car in initially because the check engine light came on. A few days later the issue was supposedly fixed after replacing a part covered under warranty. An unrelated visit took me back to get a tire replaced. This issue was fixed also. Now, comes the problem: Immediately after getting the tire replaced my air pressure light came on along with the check engine light. I called and they could not see my car for about 4-5 days. During these days I was forced to put air in a brand new tire daily. I finally had an appt and left the car with them all day. Upon picking the car up I have a bill for $160 dollars. They said it was $98 to diagnose the check engine light which read that I had low oil. They did the oil change for about $35 I guess and chared me $15 to check the pressure sensor. They said Nothing was wrong with the pressure and since I just needed a oil change you have to pay for the diagnosis. WHAT?? Being a woman I thought it was just me. Fist off if it was just an oil problem my OIL LIGHT would have come on as it usually does to tell me to check my oil. And I know there is a problem with the tire because it looses pressure daily. Not to mention they charged me $15 to check a tire THEY just replaced themselves. A day after paying for them to basically give me an oil change both lights came back on and the pressure was dangerously low again . I brought it back and they tried to tell me they were going to charge me another $98 and $15 to diagnose the same problems. After speaking with the SM I let them know I would not be paying them any more money. They checked the lights and actually looked at the tire to find I needed a similar part to the initial