1st Central Car Insurance and Autonet Insurance both charge £15 for the privilege of doing business through a call centre.
Hastings Direct has a £12.50 call centre arrangement fee, which is in addition to other levies, including £5 for sending documents by post.
It is feared that older people will be hit by the charge because they use phones rather than the internet
The extra charges have come to light since an industry requirement for greater transparency was introduced.
Caroline Abrahams, of Age UK, said: "This is undoubtedly rough on the millions of older people who are not internet users, many of whom can ill afford to pay a surcharge."
Complaint handling group resolver.co.uk said it had received around 1,000 complaints about insurance in the past six months – with around a quarter relating to admin fees.
The charges have come to light for the first time since a call for greater transparency was introduced
Spokesman Martyn James said: "It's absolutely astounding that a business would charge people for speaking to a customer service adviser."
Hastings Direct said: "We never charge anyone making a general inquiry or existing customers to phone us. Hastings Direct is largely an online insurance broker. A very small number of new customers want to complete the full buying process on the phone."
1st Central said: "Most insurers charge adjustment fees. We maintain clear communication with our customers to ensure they are aware of this."
An Autonet spokesman added: "All our fees are fully disclosed."