There've been a couple times. I make a distinction between frustration at the company and the person, but sometimes you run into reps that are willfully unhelpful or actively malicious for their own gain.

Two cases come to mind. I've had an ISP rep call me about updated prices, who then proceeded to try and sell me a broadband and streaming bundle subscription. I would have gotten a slightly faster speed, plus the streaming BS. Same price as I was already paying.

I specifically asked if unbundled contracts had also been changed, and the dude said "no". I checked the prices online while still on the call, and the bastard was straight up lying. Without the streaming bundled, the price was lower and came with even more speed. I told him this, and he asked "oh do you want that then?". I replied "yes, but not if it gives you a sales bonus", so I hung up and signed up for the new contract via the ISP website.

In the other case I was shopping for jeans, and the store rep repeatedly handed me elastane-ridden skinny jeans a few sizes too small, insisting they'd look better, even as I kept telling him the exact size I wanted, and that I preferred the 100% cotton denim, loose fit jeans. At the fourth pair of skinny jeans I told him to fuck off, and just went through the store myself until I found what I was looking for.