We've never had an issue with Telmex. The two times that our modem burned out due to storms or lightning strikes, the serviceman brought us a new one in less than 72 hours.
I'm sure there are lots of bad as well as good stories about Telmex. We love them and wouldn't think of changing our service. We live in a rural community to boot and our road is not paved and over a km long. We are "supposed" far from the register box that the signal should be very low. We stream Netflix, use two laptops all at the same time without an issue.
Once in a blue moon, the service may go out for a short time but that's about it.