In this day and age I would suggest yoy look at the stores terms and conditions. Somewhere its will have somthing along the lines of " whilst every reasonable care is taken, customers must realise"
Unless you can prove any form of negligence i.e that shelf is different from any or every other shelf in the shop., you don't have a claim, also I aren't there signs along the lines of "ask a menver of staff for assistance"?
In this day and age, all shops are very careful about T&C's.