If you are using a service especially, you will want to ask customer service if it is possible to speak with a few satisfied clients about their experience with the company. The credit repair service should have access to all the clients' personal information, including phone number. And a prominent service should have at least one or two recently satisfied clients willing to speak with you.

In any event, just perform your due-diligence beforehand and "go with your gut". Remember, this is your personal credit life you are entrusting to someone. Make sure the credit repair program you choose is worthy of that honor.