Night before sailing told only port visiting been cancelled

Have been loyal to P&O for over 20 years but after this last cruise will certainly think again before cruising with them again. We booked a short 4 night cruise from Southampton to Amsterdam and back on Ventura. On the Monday evening we were departing the following day we received an email informing us that we couldn’t dock at Amsterdam as the locks were being repaired we were going to Cherbourg and LeHavre instead. We were given as a goodwill gesture £100 per cabin to spend on board. If we could have done we would have cancelled the trip. You don’t pay over a £1000 to travel to places you can go on a ferry for a day trip if you wish. We were asked to board at 12.15 which we did but cabin wasn’t available until 15.30 and 16.45 before our luggage appeared that was wet. As another passenger has said all the little extras have disappeared like the “Good Night “ chocolate and the turn down of your bed, clean towels only once a day. Asked for a table of 8 and was given a table for 2 against a wall, when we asked to move the following night we had a table for 8 but only 6 people sat there at any one time. All check in details had to be downloaded at home including a photo for your cruise card that you didn’t received until you reached your cabin and it was in an envelope on the rack by your door. Ventura was a new ship to us so we hadn’t a clue where anywhere was as you didn’t get a map until you got your cruise card. When you buy any drink you don’t get a receipt so don’t know what you have been charged until you pay your account at the end of the cruise. Because of the change of port there were no trips arranged and at LeHavre they had very limited shuttle buses and it was 30mins walk into the town. Tried to book for the theatre on line but was told fully booked, after queuing for some time at reception my husband was told we had been booked in for all shows. They apologised and said that their internet site had had a problem. P&O will have to change back to some of their old ways if they want to keep their loyal customers or they are going to leave in droves.