The two-minute call
How to make the call you have been avoiding, so it takes two minutes instead of two months.
Here is the whole script. It is shorter than the text thread you were going to send instead.
"Hi, it's [your name]. I'm calling because I want to clear something up directly instead of over text. Do you have two minutes?"
Then say the one thing. Not the history. Not the five other things. The one thing you actually need to change. "I need you to stop messaging me." "I need the fence moved back to the line." "I need the money by the end of the month." Then stop talking. The silence after it is the hardest part of the call and it is also where the call gets made. Let the other person fill it.
They will say something you do not like. Let them finish. You do not have to agree with it. You are allowed to say "I hear you, and I still need the thing I said." Then, if you can, offer one concrete step you will take. "I'll stop bringing it up if you'll do that." "I'll send you the survey." "I'll give you until Friday."
Then end it. "Okay. Thanks for picking up. I'll leave it there." You are done. Two minutes, maybe four.
What you will want to do instead, and why it is worse
You will want to text first "to give them a heads up." Do not. The heads up becomes the conversation, and it becomes it in the worst medium available.
You will want to write it all out first so you get it right. Write it out if that helps, but then call. A written version delivered by text has no tone and every possible tone, and the other person will hear the worst one.
You will want to wait until you are calm. Wait an hour. Do not wait a week. A week is enough time for the other person to decide, on the evidence of your silence, that you are the problem.
You will want to bring up the other things. Do not. One call, one thing. You can make another call.
When not to make the call
If you are afraid of the person. If they have hurt you or threatened you. If a court has already told either of you not to contact the other. If you have already made the call and it did not work, and now they are the one who keeps calling. In those cases the answer is not a better phone call. Go get help.
Everyone else, and that is most people in most disputes, is one uncomfortable phone call away from not needing a lawyer. I say this as the lawyer.