I’m on our community committee so while no expert I have an understanding I think. You should first look at the Horizontal law which if you pm me your email address I’ll send you the English version I have. You also have a copy of the statutes which will tell you to which buildings, blocks or phases the statutes apply (ours do.) If it names all of the three phases then I would think that all of them belong to one community with one elected president and one elected or appointed administrator (the president can be both.) Have you had an AGM yet, something you must have ever year? The thing to remember is that as an owner you own a share of the community and therefore have a right to know everything that goes on in that community.
I bought a book called “You and the Law in Spain” to quote Amazon “The Complete and Readable Guide to Spanish Law for Foreigners (Including Horizontal Law in English)” by David Searl which I found very helpful with all matters relating to the Spanish system.
The community “Rules” should be based on the statutes and therefore enforceable if not based on them then not enforcable. Depends on the rules really, if you don’t pay your community fees, the president can ask the AGM for permission to take you to court and ask for seizure of your property and then sell it to recover the community charge. Getting someone to take down the towels from the terrace is trickier, no matter what the statutes say!