I like VTG. Their middleman roles of useful comparisons of various cruises from same port & to destinations, prices etc by different operators, are tedious setup & investment capitals.
It’s well known that once you paid the initial confirmed bookings, all further progressive payment's & dealings like cancellation or upgrade of rooms are done directly with the principal operators. Intermediaries don’t come into the picture anymore. Same like you buy a designer watch from a retailer. Any change of prices by the manufacturers, a few days later, is a non event for you.
Recommendation: VTG is reliable