Best Carbon Monoxide Detector in Phoenix AZ

We had a backed up drain from our washing machine. The night before the drain was backed up.When the technician came he was able to run water down our drain without issue. Didn't offer to snake or camera our drain to see if there was something in the drain, just ran water down it.The next day when we hooked up our washer it immediately backed up again. When I called the office to see if there was anything they can do they wanted to charge us for a separate visit rather than fix the issue they didn't even try to identify.