Ouch!
But, it has been explained in post #2471 why Azamara discourages the use of other detergents.
If the detergent is so important to you or your clothes, why not wash everything by hand?
Or, alternatively, bring clothes that do not need special treatment.
Also, AFAIK, UV-resistant clothing can be laundered without 'special' detergents. I checked the wash labels on all mine, and there is no reference to use of a 'special detergent'.