MTG Salvation

Okay so a little background here, I work as a manager of a very very small or micro retail/business.
We give discounts to frequent buyers and bulk buyer. But we are not on a real wholesale or distributor level.

Anyway a few of my customers often ask for discounts even if they do not purchase in bulk or frequently, but their reason is [we have been buying here since you were a child]. It is a moot point really as she buys from other people more regularly and only comes to me as her last resort.

Now here I sold her a product yesterday (Net Bags) for 55 pesos, as the agreed upon price. My regular selling price is 70 pesos. All is well. Then this morning, 1 day after her last purchase, and I charged for 55. However she exclaims that yesterday I told her it was 50 pesos and with a raised voice she said it should be 50. I said "I did not say that".
How do you deal with people who change the words you say? What is this act called?
There are a few others who also change or add words to what I say, sometimes not 5 minutes after I say them.

Thia one was really appalling because I told her she was changing my words, so I let her be for a while perusing my products, figuring it would be better to semi ignore her. She kept on asking for discounts on some other products and I was reluctant to give her a discount, fearing she would yet again change what I say. Then I calmly explained to her that I was afraid to say something because I was afraid of her changing my words, she got real mad and said "I DID NOT CHANGE MY WORDS!" then she proceeded to say that she was asked politely that she thought I told her it was 50. Then I said it she just changed her words again. She then again said she did not. I said she changes my words, she changes her own words then it escalated after that.

I don't like it when other people change my words because I don't really say much so I only speak when necessary, because of people like her.

It’s called gaslighting.

Necro.