Hi Janita and welcome to the wierd and wonderful ways of Spain.
We had the same situation on our Urbanisation when we first became a Community of Owners four years ago. You will find that it is the Administrators of your Community who are taking the money not the President, so please be gentle with him/her when you meet. Saying that I hasten to add the Administrator is collecting the fees for your Community by any means available to them, which many Communities would envy!
Even though we (my partner was the first President on our Urbanisation) paid our first Community charges in cash as soon as the Community was formed, we discovered when we got our bank statement that the then Administrator had taken the fees again from our account without our permission. When we queried this we were astounded to be sent by return email a full list of owners name and their U.K. / Ireland/Spanish addresses, their passport numbers phone numbers and their Spanish bank account sort codes and account numbers. Needless to say we informed all our owners about this situation and destroyed the information BUT we had been sent this information by a man (the "Administrator") who has met us once and had no idea if we were honest people or not!
It would seem, and maybe someone else out there has been in the same situation, that the builder has all your bank, passport, address etc., details from the agent and he passes them on to the Administrator. It seems to be the done thing in Spain for any one to take what they like from your account and you have to stop the payment within 21 days if you think it should not be paid out! (again I stand corrected if I am wrong). I have never signed a direct debit form here and money dissapears from my account on a daily basis. Although I have to admit that I have now worked out where it is going and why!
The only saving grace in this situation is that they money needed to be paid and you have probably saved being "fined" or named and shamed as it would seem that you did not know that these charges were due. There is a lot of information on this excellent site about Communities, Community fees the role of a President, Administrator etc and most of them can be found under the title Owning a property - Running a Community or just put your query into the search facility.
To answer the query is it a rule that you have to pay monthly ? you need to see past minutes from your Communitie´s Annual General Meetings (A.G.M.) or Emergency General Meetings (E.G.M.) Ours is relatively low and owners pay one year in advance with a ten percent discount for payments made in the first 12 weeks after the A.G.M. Payments are then at the normal rate for the next 12 weeks and then there is a twenty percent fine/penalty added for payments made after this date. All these rules were made at the A.G.M. ´s or E.G.M.´s by majority vote of the owners (i.e. not the President)