Harry Potter
First of all, this is a public traveller-to-traveller discussion forum, not the SBB customer service. Most of us here are probably not able to comment the specific inconvenience you‘re experiencing, as those of us who still have an occupation are usually working somewhere else (rather way below 3000 m altitude).
Secondly, next time you‘re closely looking at a standing train in Engelberg (waiting forever for departure), you might notice that the term „SBB“ is mentioned simply nowhere on those coaches. However you‘d rather find terms such as „zb“ or „Die Zentralbahn“. So in fact, those trains are run by a different train operator than SBB. Therefore even the SBB customer service couldn’t help further, as it‘s not SBB deciding about whatever timetables relating to Engelberg.
In fact, Zentralbahn have their own website, which also features a contact form, a phone number and even a customer service mail address for complaints.