Price adjusting on existing stock

I went to Mr Price home to buy glasses, to replace some of the ones I had previous;y brought from there and where broken.

when I picked up the glasses I noticed the prices had been rubbed off the glasses. I found one with a price tag of R9,99 on it and took the four glasses I wanted to the till.

the price they rang up was R11,99 I questioned this and the teller called the manger.

the manger came and rectified the price only on the glass that dir not have the price rubbed off.

Surely this is not the way to conduct business.