Hey Bec, I will do my best to answer this question for you as well as I can.
Firstly,
if somebody is a farm, then anyone in the alliance or it's wings is entitled to farm them. Basically, first-in first-served. While this may be frustrating at times, believe me when I say it's more frustrating to be told
do not farm him, do not farm her... etc. And personally, I'd rather the loot be taken by an alliance member than someone who's part of another ally; as I'm sure they have no reservations about raiding your farms.
However,
if you have only recently cleared a village for farming, then it is expected that you will be allowed to farm that person without competition for at least a week, especially if you took heavy losses clearing the village. So in this case, you are perfectly entitled to expect your neighbours to lay off the village for a while to let you profit from your hit. Of course, there are people out there (in the alliance too, I am sure), who will not observe this simple rule of ettiquette, but unfortunately we can't do more than remind them, or put up with them.
So, in your case, you've been farming the said person for 5 months. In that case, absolutely anyone in the alliance or wings are also perfectly justified in attacking that person as well. You can ask them to stop, but it is perfectly in their rights to refuse. But the message they sent back displays a level of immaturity which I'd rather not see in this alliance. I expect everyone to be civil and good-mannered to their fellow alliance mates, as we're supposed to be working together, not against each other.
I hope that answers your questions, and if you want to discuss any further issues with me, feel free to message me ingame.
- One Man Army