This! I totally agree.
I tend to get...not really intimidated, but feel shy or ashamed anticipating how I might be treated, when my request is totally reasonable and it is only the store atmosphere created by some SA that makes me feel ashamed sometimes. I admit that I mostly shop at H.com or resellers for B or K because I spent a long time dreading going into the store.
Fizzywater, just go in and ask for an exchange as if you are at any other "luxury" store. You have a reasonable request and don't let prior bad experience make you feel otherwise. If they say no, you can decide if you want to sell/give away your current CW to buy the preferred one or not.
I used to hate going into my store because my SA always made me feel bad and her response to any inquiry or problem was to say "no" and pressure me into making a new purchase to solve the problem. I switched to a new SA (which is also awkward due to hovering and long looks from SA#1 when I come in to the store), but now my problems are solved with grace and the experience is fun again as long as I avoid SA#1.
Examples: wanting to exchange NWT silk item with a run in it. SA#1--> skeptical, "it's ok, no one can see it, you have to exchange for the exact same one and we don't have any more, you need to buy this scarf ring so you can't see the run..." to SA#2-->"I'm so sorry that happened! I have reserved it for you with another new CW that just came in that I think you might like, I know it's hard for you to make it in to the store so no rush!" Another example: wanting to spa an item: SA#1- "I don't think you want to do that....It would take too much time...It would be too expensive...Just keep using it...Buy this twilly to cover the mark..." SA#2- "That is so beautiful (shows other SAs). It will have to go to Paris but I definitely think it is worth it, it is so special, you want to make sure it lasts forever."
Fizzywater, when you go in, if your unkind SA asks to help you, just say "I'm just looking around right now, thank you." Walk around until you find a newer SA who seems friendly and doesn't know you/your relationship with unkind SA, and when they offer to help you say Yes! That's what I did