Never understood the reason to be the one to contact NCL about a M&G. You don’t get anything for doing it other than getting to pat yourself on the back. Definitely a first world issue getting so upset.
Those times are woefully incorrect. You can generally expect to be able t get off the ship within 15 minutes of arrival time. All that other stuff is taken into account when setting arrival time.
All it takes is a phone call to cancel an excursion and get a refund. If within 48 hours of sailing it is given as a refundable OBC, else it goes back to the method of payment used.