My grandmother wasn't only a "let me talk to your manager" type she was a racist and advancing dementia completely turned off her filter for that. I've blocked out all the context behind it other than I took her to buy yarn and something went wrong. I think maybe they shorted her a couple bucks or wouldn't honor a coupon or something. Whatever it was ended in a "let me talk to your manager" followed by a tirade to the manager about how they shouldn't be hiring Mexicans. I just remember having to talk over her and say, "Oh my god you can't talk to her like that. Nothing you just said is ok" followed by me trying to push her wheelchair out of the store as fast as possible with her digging her feet into the ground trying to get me to stop so she could go back to trying to ruin someone's day and me wondering if I'd go to jail for elder abuse if her ankles snapped in the process because nothing was going to stop me getting her out of that store. I got her into the car and then went back in and apologized till I was blue in the face. I wish I could say it was an isolated incident but it definitely wasn't.
If by any cosmic chance any sales clerks or phone reps that had to deal with my grandmother read this thread I am so so incredibly sorry, I apologize on behalf of my whole family and I'd give you a hug if I could.
As an interesting side effect of caring for her, I have a tendency to wander off and pretend to look at things when we get to the register if I'm with someone and I'm not the one paying. I think she gave me an honest to god phobia.