Right. I've written a little script for Cacti, and I'm going to use it to show Telmex just what I mean by "intermittent DSL downtime".
The orange bars indicate service outage. Every time this happens, my IP changes as an additional bonus. This has been going on since I got the subscription months ago, and despite numerous complaints and their seemingly sincere attempts at fixing the problem, nothing has changed. Pity me.
Update: I made the trivial script available. It takes one input (host to ping) and returns two outputs (avg latency and loss %).