SOP for a PhD in Finance for top US business schools

Hello, My future major is Ph.D. in Finance and I intended to apply to the top 20 schools in the USA (Chicago Booth, Berkeley, North Carolina & ...). I have written my SOP and sent it to my supervisor and he mentioned mistakes in the sentence structures which are not used by Americans and may cause rejection by the admission committee. He suggested giving it to a native speaker for editing or writing it from scratch. as my deadlines are Dec 15, I will be thankful if I can use your help.
Thanks