Hi Stuart, yes this has happened before. The case I know is from one of the properties I manage and the fact was that it did not have a meter! But there were bills and they were paid for as well. No sensible answer to that was given and once installed a meter it was on the wrong apartment as the pipemarks were not corresponding to the right apartment. Whic left a tenant of us without water for 5 days.
Another thing that moght have happened is that all your billas are paid but the original connection fee was not. I only have that experience with the electricity company though.
In any case you best go over to the aguagest office in San Javier and talk to them in person. Sometimes there is someone who speaks English as well. If you need more help just let me know.