Whenever I predict a downtime it happens two weeks later and for only one week, and when I don't it happens for a whole month. Damnit.
Good thing is, my family got a new phone service (and thus, new line and new ISP). After two days of trying it out, I have concluded it's way better than my previous ISP, since the speed is now constant and I haven't experienced a single disconnection yet. The only two things that bother me are that this connection can't multitask very well (JDownloader takes all the bandwidth, need to reduce it so it can share) and the router configuration is locked and requires a password. This new ISP uses a WiMAX antenna and it's Axtel, if anyone cares.
One month without internet sure is boring.