plumber with special camera needed

We have a blockage in a drain pipe that serves the toilet and the shower next to it. Despite 3 tries, our plumber has not solved the problem. The last effort involved 3 guys and a device that blew air at high pressure thru the drain pipe. That fix lasted about 3 days. Obviously, we still have an obstruction somewhere. We have heard that there is a camera that a plumber can put down the pipe to find where and what the problem is. Has anyone had experience with this, and if so, can you advise as to who has one of these cameras? TIA.

Thanks. I know Jose--will call him tomorrow.