I Got My Belt And Oil change But for Some Reason M...

I Got My Belt And Oil change But for Some Reason My Car Was Exhilarating (Driving) On Its Own slowly went To 10mp Then 15 Next Thing I know Its Going 40 On Its Own People!!!!! It Hardly wants To Stop And When Its In Park It Sounds Like You Are Pushing The Gas While In Park But I WASNT!!!! Im Very Unpleased And They Will Be Hearing My Mouth!