If a registrar is making you feel as though the registration audit is a kind of consulting service, it's a misunderstanding or worse.
I really want you to understand that an organization needs to know, on its own, how well the audit program is functioning. The audit process is intended to assess compliance and, running the assumption that your QMS is responsive to such input, provide input suitable to recognize opportunities for improvement. If this process is not itself internally assessed, the organization runs the risk of not knowing when a gap in auditing exists. Clause 8.2.3 says we should monitor and, (where applicable) measure QMS processes, and that the methods are to demonstrate the ability of processes to achieve planned results. These QMS processes include the internal audit process.
By delegating the matter of assessing internal audits to your registrar, you are failing to recognize that you understand the need to examine how well you are doing assessments on your own. Even a small organization should be able to do it--you can use methods like trade internal audit services with another organization; you could be finding one via your area ASQ chapter.