A READER changed her hairdresser last Christmas and switched to Peter Mark because it was advertising 20 per cent off hairstyling all week.

“It saves me about €9 a visit, which all adds up and is great,” she writes. “At the end of every visit, the staff always make a point of saying, ‘So with 20 per cent off, that’s €34’, for example. I sometimes get texts from them also reminding me about their 20 per cent discount.”

So far, so what? you might think. Well this 20 per cent off offer applies all week, no matter what day or time, and has been running for at least nine months.

“When does a reduced price such as this actually become their ‘normal’ price, if that makes sense? Or can they just go back to their higher price at any time?”