Once again P&O missed port calls

We took a Christmas cruise on P&O’s Aurora from 21st Dec to 6th Jan. Although we had a good time on the cruise, I would never cruise with P&O again due to them repeatedly cancelling port calls on their cruises. On this cruise we had port calls to both Lanzarote and Madeira cancelled (for safety reasons). On the cruise we had with P&O last September we had a call to Valencia cancelled. On the trip we had booked to Iceland later this year we were informed that the calls to Northern Iceland and The Faroe Islands are being changed to Tromso and Liverpool (for operational reasons!!). We were told by P&O that these port changes are not considered significant and therefore we could not cancel the cruise without the loss of our deposit. My brother has been told his cruise with P&O to Norway on Iona will have two port calls cancelled and they will now be scenic sailing days. What on earth is happening with P&O and why are they repeatedly cancelling port calls?