Voting in Belgian Elections - HELP!

I just received a convocation to vote for the Belgian municipal elections. It is the first time I receive this in 7 years living in Belgium. I know it is compulsory to vote here and there is even a penalty mentioned for no-show: Les citoyens belges et non belges qui sont inscrits sur la liste des electeurs ont l'obligation legale de voter. Si quelqu'un s'abstient d'aller voter sans raison valable, il peut etre condamne par le tribunal de police et se voir infliger une amende.

My questions:

How did I get enrolled in such election list? How can I take myself off that list, preferably retroactively so that I am not forced to go and vote on 14th October?

I have already asked the question to my commune (by email) but didnt get any answer.

Thanks for advising.