Functional format is best for those who are switching their career or have large employment gaps on their resume. In this format, you dont have to list the joining or resigning dates of the previous employments. Functional format will hide your employment gaps or your job switching.
Add in a list of skills Your resume is no place for modesty. Highlight your skills especially if they are specific to the job youre applying for and list where you gained experience with that skill set. Instead of being general give concrete details and highlights. For example list your experience with Microsoft Office or even a particular piece of software over computer skills. Make sure to include plenty of competency statements.
No sample resumes are accessible. A competent resume writing service will provide a number of samples for review. You can assess the quality of their work only if have these samples. If there are no samples available on their website ask them for the specimens of their work. If they are unable to provide satisfactory examples of their work you had better opt for another service.