Should I invest in a professional resume writing service?

Yes!  Firstly, most people do not know what makes a winning resume or cover letter.  There is a lot of incorrect and conflicting information on the internet about resume content and resume formats, and it can be very confusing.  You may have a friend or relative who is an ace on the computer offer to write your resume, but they may not have the right knowledge or skills to do so.  Secondly, industries and even organisations can differ as to what they like to see on applications, and these change over time.  What used to be ok, just isn't now. And finally, hiring a professional resume writer is an investment in your future.  How much would it cost you if you missed out on that next job, or took weeks longer to be hired?