What you describe is a prime reason to have a travel agent rather than to book your reservations directly. Although I agree that customer service is important, whether for a client or for a travel agent working on behalf of the client, the TA knows which rez agents are most reliable and also knows whom to turn to for assistance in unusual circumstances. Often TA's can offer better fares than if you book directly with any cruise line. If we have group space blocked, for example, there are discounts and amenities that you will not learn about from a rez agent at Viking. Other times there are promotions about to be released to the public, and we can tell you about them before the cabins are sold out.
There's a motto in the industry which is soooo true: Without a travel agent, you are on your own!"