I had a smell of sewer gas in my basement. I have an older house with clay sewer pipe. I contacted Sewer Squad and they responded the same day and arranged for a camera inspection by Nick, who is professional and explained everything clearly.
Arsen and his helper came 3 days later and taped off the room to contain any dust and then cut into the concrete floor and remove the blockage and put in new cleanouts, all within about 3 hours.
Mike, Mitch, and Josh came a week later to do the outside work to line the clay pipe to the city line with a fiberglass and resin liner. They were polite, fast, and did yhe work in less than 2 hours.
For all of these jobs, the people in their office send text messages and email along with a description of each person that is to arrive, so that I knew what was going on.
They are fast, efficient, and good at communicating.
I suspect they aren't the cheapest but you get what you pay for, and as I would not want to have to do repair of a sewer pipe more than once, I think it's good to go with experts.