Grumpy customers are part and parcel of the retail industry but did you know there's a day when shoppers are at their grumpiest?
New research has found customers reach peak grumpy on Sundays while shoppers' happiest day out in the stores is Friday.
So, should shops simply not open on Sundays?
And what other changes should they make?
Customer Radar CEO Mat Wylie spoke to The AM Show.
Watch the video.