I am sorry about your situation, but sudden changes in schedule happen pretty much to any airline in the world (and LATAM is not an exception). The decision not to contact LATAM yourself (and assuming beforehand that their customer support is bad) as well as your complain about lack of phone service in the area - it's not really LATAM issue, it's your personal choice in this case.

As for the reliability - LATAM is actually not that bad (statistically speaking). Good luck with finding a better alternative here is South America, and especially in Chile and Argentina