My car is not going past 20 miles per hr after a mechanic added transmission oil on my car. They have told me the brakes is what is wrong with it because it wont move but it will accelerate. The car will turn on and once I press on the gas it feels as if it has the hand breaks on I press down on the regular breaks and the car starts moving but only for a bit. After that it does that thing where I press the gas and it accelerates but stays in the same place... Can anyone tell me what might be wrong with it.