Why are they asking for our opinion on opening hours ?

We were never asked when they changed the hours, although they claim customers wanted to come to the store later on a Sunday & it was their reason for the change. Possible that the new times have not worked for them ( finance and staffing ) and they want to revert back to the old opening hours ?. I have noticed that going into the store (since the change) at around 17.00, the store is empty, so it is not working for them. When the store was open 11 to 17.00, from my observations there were lots of people at 11.00 and then the store was very busy between 16.00 to 17.00. They have the figures for hourly transactions.

I really do not care what hours they are open - the way we shop and the options that are available are numerous & changed beyond recognition.

It is a private business, they should know what is best for their business. They have the data (financial) that would guide them on what is best for them, so go ahead and decide Sainsbury's.