Never tried United Plumbing, just recently used Ben Franklin's Plumbing to replace my sewer line from house to city. Finished the job 1st day than backfilled the 2nd. Sounds like you are having the same issues I was having but mine remained unclogged for 3 or 4 months before it started backfilling, and gurgling toilet. If you have a clean-out drain I'd have them send a camera down to inspect your lines. I didn't have the luxury of seeing all my lines because I had a yard trap 15 or 20 feet from house they couldn't get past and I didn't have a clean-out anywhere outside. Best of luck