Fifth cruise with their company(Carnival, Princess, Holland America) in past seven years. Will never cruise with any of them again. Changed our itinerary without notice causing difficulty for friends who travelled 900 miles to meet us at the omitted port. If they would have advised us of a change in itinerary, we could have cancelled our cruise or our friends could have made different arrangements. On board, we were required to use their on board app which had numerous problems, especially at dinner. Two nights it didn't work at all and we had to wait in line to be manually queued to be seated. Lot's of grumbling about level of service. Food was unavailable on the Lido several hours a day, a change from the 24 hour buffet we were use to and expecting. Complaints were met with apologies but no adjustments or credits. Our only recourse was to withhold our gratuities.(We took care of our room steward, the only person that truly made an effort). I can't believe they would be so non responsive to us and flitter us away as continuing customers.