Most of clients does not have account here. If dishonest man I can easily do that but I'm not.
I have a hard time believing that.
With a service like yours, any testimonials, especially from trusted people, is essentially needed if you wanna advertise this here. Using their feedback as testimonials is not being dishonest, if anything, it could help you push this service very far here because if your testimonials are legitimate, then you can easily avoid scam accusations that would otherwise put a hamper on your service.
Also, where are you finding clients at exactly? Why are you unwilling to provide testimonials?