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.
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.
The resume that lands you the job interview isnt a simple listing of your past duties or work experience. It has to convince readers that you have the required skills and abilities to exceed the expectations of the position so your resume should be structured in a way that arouses employers interest in you and gives them reasons as to why you are more qualified than others while encouraging the employer to get in touch with you for an interview.