What the new guy did is unethical. He changed the terms of your insurance without your permission. Depending on the state laws, he could actually lose his insurance license for that. I would drop that new guy in a heartbeat and I probably would get out of the office entirely because if your agent is in the same office you can't be positive the new guy couldn't do anything.
I once had my insurance agent merge my policy and my roommates seperate policy into one. With her name as the primary insured. They got a blistering phone call once I realized what they did, made them seperate the policies, told them they were on thin ice with me, and if they screwed up ANYTHING else I would be switching. About a year later they made a mash of things when I got a different car, and I actually went to another State Farm office, told them things were messed up, I needed them to straighten everything out and they were my agent now please make that happen. Got an email from the old guy a while later asking why, and I told him. I'm not an unreasonable person, but I do expect competence.