I think you really mean can you insist on a marked car or superior to attend. No. You do not have the right to insist on a marked car or a superior just because you doubt their authenticity.
You have the right refuse to comply with their requests if you have reasonable grounds to believe they are not real police or the requests are unlawful. 'Reasonable grounds' is an objective test and is not based on what you personally believe, but what a ordinary person would believe in the circumstances.
You have the right to call the police yourself and ask if they are legit.