We call a company to remove the roots from the sewer, because where having a sewer backup. Now it start to smell like sewer in the house, do you think they damage something Its was not like that before they remove the backup on our sewer. What can you suggest for as to do. Its hard to get answer from this company/

Sounds (or smells) like they breached the actual discharge line somewhere and now they don't want to fix their mistake. The pipe will have to be replaced and that involves digging it up and relaying it in the broken area and that can result in a huge repair bill. Your commend of it's hard to get an answer from the company speaks volumes as they know they did the damage to the pipe and now they are going to play "dumb" on you. Best to call another company and get an estimate for the repair and then take the first company to small claims court for the cost of this repair.

At what point did they insert their rod to clean out the roots?

Twinkie:

Breached sewer lines don't necessarily require digging up inside. Sewer pipes can be re-lined without digging.

Make sure the cleanout plug(s) that they used isn't leaking.

Its important to picture the plumbing system in your mind's eye. Big pipe comes from the city and enters the house, turns up and goes out the roof. All other drains tap into a part of this pipe and have their own small traps. Only way for sewer gas to come inside is for a trap to be bad or a breach in that big pipe somewhere inside the home, like where they took off the clean out cap. Is the cap sealed back in place properly?

Let me give you some relief with the roots. If you wish to control roots RootX or Robics Foaming Root Killer that contain Dichlobrnic are two products you could try.
A less expensive way would be to call around to garden supply stores and ask for fine grain Copper Sulphate. Put a 1/2 pound in your toilet and flush it down. Repeat in 6 months.
Hope this helps and thank you for rating my answer, Tom

How do tree roots get in a sewer line if the line isn't breached? I've read a lot of threads here about tree roots clogging up a line. Just not clear how roots get in a sewer line that's a closed system.

Roots can't get in unless there is at least a small crack in the line. Old lines were laid in sections and each joint was an opportunity for a hair sized root to get inside. Once a hair sized root gets inside a pipe it starts growing full sized in the pipe. Tom's recommendation will prevent those roots from growing by killing them off periodically. A solidly glued PVC drain will not get roots inside unless some other force breaks the pipe.

Got it. Thank you.

How do tree roots get in a sewer line if the line isn't breached? I've read a lot of threads here about tree roots clogging up a line. Just not clear how roots get in a sewer line that's a closed system. Bob gave you a excellent explanation.
One way roots enter a closed system is through the joint at the street raiser. I've been retired for 20 years so I have to assume that they must have come up with a better way but when I was out in the field we caulked the joint with oakum or rags and filled the rest with cement. Over the years the cement shrunk allowing roots to enter. Cheers, Tom

Thank you Tom.