I assume these are clotheslines on common property for general use? If so, and the EC won’t respond to your suggestion put in writing, I suggest 1) talk directly to someone on the EC in person, face to face. Perhaps they are are snowed under with other things? Offer to organise a tradesperson to move one to be higher. Point out the long term benefit of having them at different heights so that one better suits tall people and the other better suits short people. 2) If that gets you nowhere put it to the next general meeting. A decision of a general meeting overrides the decisions of the EC and they have to act on the GM decisions.