Allowing Frustration

Ok, so yesterday I had a frustrating experience. Briefly, I was trying to change to a new phone and then got locked out. Here is the model for that:
C: locked out of phone
T: they must have messed something up
F: frustrated
A: snappy and curt with sales person (not the person I want to be!)
R: still locked out of phone, now have to reset whole thing

So usually when I have done models it has been to change the thought to change the feeling. However in this case, I do not want to resist feeling frustrated. It was a frustrating thing. What I would like to be different is how I act to others when I feel frustrated. So I am having trouble conveying this into an intentional model. This is what I have come up with:
C: locked out
T: ??? It is ok to feel this negative emotion?
F: frustrated, ? accepting of frustration
A: sit with frustration until it passes
R: not lashing out, still locked out but that’s ok

Also, when you are in the middle of interacting with someone, say at work or in this situation, where you can’t just leave to sit with your negative emotion, what do you do? I am starting to accept the 50% negative emotion thing. And although I have intellectually understood the not resisting emotion, I am only just beginning to be able to do this.