Just in case, how can I make them to pay for my alternative flight at another company with minimal hassle? What's the smartest way to approach them when a flight is cancelled?
There should be a complaint form/refund form on their website. Or you contact their customer service. They will probably be flooded though, so it might take a while. The offer for a refund or a new flight with them should be in the mail they send you if your flight gets cancelled.