CAs who submit ITR using their own Logins

How do you find CAs who submit your ITR using their own login? Usually these CAs file ITR using tax payer’s logins only. But in ITR portal there is an option to authorise someone else to file on your behalf (it has some specific term to denote I guess). So how do you find such CAs? Has anyone been using services of CA in such way? How much do they charge?