Letting the pastor know about the fact that you were sworn at when calling a phone number in the church's pamphlet would not have been tattling. It would have been doing the church a service. The only way an organization can fix problems is if they are made aware of the problems.
By the way, I've had some real problems with certain telemarketing schemes. If you start out with a reasonable response to a telemarketer, "Sorry, I'm not interested,", you can tell which type you are dealing with. The ones who are just legitimately trying to make a sale will say, "Thank you," and hang up.
The problem with the telemarketing industry is that there are a few who are deliberately trying to get around the "Do Not Call " list, and will continue to harass you. If you press "1" to have your name taken off the list, you will get even more calls. There are a couple of these schemes where you will get 3 calls in one day. You also get calls from the same scheme from different numbers from different area codes. If you answer one of their calls, they know that someone is there and will keep calling. I did some internet research on a couple of these numbers and they are well known for they do and there is very little you can do about them. You can ask for their information to report them for breaking the "Do Not Call" policies, but they simply give you false information.
One of them has to do with alarm systems for the elderly, another starts with "Hi, my name is Heather". The thing is, by getting mad and swearing at a caller, the guy from your church is upsetting people who nothing to do with the harassment, including cold callers who don't deserve to be treated like that.