She was a cashier, only deal with payments, and not an SA who assists in selling. And you only quoted half of my sentence. The full sentence is 'I think her constantly interrupting and talking over me at the end was her attempt to trigger me, probably after realising she made a mistake in mistreating me.'
I am sorry. I assumed people understand what 'you need to use your own card (for online payment ) though' implied. And therefore talked about how it felt to me. I realised now it was not clear.
Interestingly, you decided the intensity of my feelings is too strong. Do I feel I need to explain what happened further? No.