Rio Tinto Machine Learning Engineer interview questions

A ridiculously long technical challenge which took more than 20 hours and I am pretty experienced geo spatial data scientist. This was to be followed up with an interview. The interviewer cancelled it 15 minutes prior to the interview under a very flimsy pretext that someone other than him couldn't find time make it. I was told that they would be rescheduling the interview, but I haven't heard from them since. They didn't even bother to provide feedback regarding the technical challenge. I have no issues if I am rejected on the basis of a solid feedback. They are utterly unprofessional, lack basic decency and do not value others time.