Shoppers Drug Mart

I was in the Shoppers Drug at 2223 Bloor St W on the 29th of July, looking to purchase a hair color.
L'OREAL Preference was on sale for $9.99
I purchased one and when I got home realized I picked the color number next to the one I wanted # 18 vs # 17

On the 1st of Aug. I returned to the store, suggesting I just wanted to switch the colors. Not a refund.
The sales lady then proceeded to do a refund of the first and then do the purchase of the second one as a new transaction.

The problem was that the sale price was over and I was told I had to purchase the new one at the regular price. From $9.99 to $18.99

The lady brought over someone who confirmed that there was nothing they could do as the system will recognize that there was a price difference. I'm sorry, but I just don't get that she just couldn't do a straight switch of the same product. This does not sit well with me as its not right and the sales staff was rude about it.