Online Check-In Always Down

Online check-in is an absolute mess. Every time I traveled with Mango I couldn't check-in online. Today my girlfriend can't do online check-in due to some "system error". Travel agent and I have spent hours trying to resolve it with Mango Support with ZERO success.

Seriously, how difficult can it be to fix your online check-in? All the other airlines seem to be able to cope just fine!