Zero religiosity (part 2)

I just found the website of the Dutch Catholic Church, and they had an email facility.

Here's a translation of the email I sent them (with some asides for lay persons)...

LS (Lectori Salutem, I thought it appropriate to use Latin),

I do not consider myself to be a catholic, but an atheist. As soon as the occasion arose I deregistered my catholicism with the municipality (the church used to get a contribution from the state on the basis of the number of registered believers). But whenever the church boasts about its 600 million members worldwide I ask myself how many of those actually regard themselves as part of the church. I for one do not. Several years ago I tried telephonicly (aparantly there is such a word) to deregister with the catholic church, but I was told time and again that this is not possible. Now I have set out on my second ‘crusade’.
Can you provide me with information, or at least point me in the right direction, for deregistering or excommunication?

Thanking you in adance.

I was told I could expect an answer within three weeks. Start the clock.