I have registered with an agency. They have offered to write my CV free of charge. Why should I pay for one?
Agencies exist to provide a steady stream of traffic to interviewers. It makes no difference to them whether the company placing the vacancy with them hires you or the next person they send. The agency doesn't care - they get paid anyway. With regard to the CV they produce for you, the quality will reflect this "scatter-gun" approach. Usually you will fill in a form or have a brief interview, and that information will be inputted by a data-entry clerk into a software package or word-processor. A document purporting to be a CV will then pop out of the printer. Then the process is repeated for the next candidate, and the next, and so on.
Agencies might handle hundreds of new candidates in a week, all of whom need to be processed and have a CV "written". Compare the CVs produced by any agency and they will all look almost identical. How will that help you, as an individual, get through the door? It's more likely to be chance and good fortune than design. With your CV, like most other things in life, you get what you pay for. As the saying goes:
"The bitter aftertaste of poor quality lingers on the palate long after the sweet taste of low cost (or no cost) has gone forever".
Are you prepared to leave such an important issue as getting your next job to a mass-produced, unfocussed and indiscriminate word-processed specification sheet?
Or would you prefer a targeted, tightly-focussed, purposeful, dynamic and relevant "Personal Sales Brochure?"