My wife and I visited ASDA at Leamington Spa as we have for 10 years. We purchased a loaf and requested it to be sliced. No staff was available to slice it so we waited 10 mins then spoke to staff who said they would get some in the bakery. 15mins no one arrived, we spoke to staff only to be told the person on the bakery was busy serving. Other customers were also waiting comenting "you'll be lucky in this store" all put their bakery items back and left. We spoke to another member of staff who said there were staff shortages and we would be better trying Tescos (not the attitude expected. We put our items back and left the store. We were so surprised at the staff attitude with no care shown and the lack of customer service, even more so from other shoppers comments that would suggest this issue has been on-going for sometime. Usually we do not complain particularly with the build up to Christmas the stores can get full but at the time we were shopping (15:30hrs Friday 6 Dec 2019) the store was certainly not crowded with shoppers.
I think you need to resolve your internal staffing issues and identify customer service training needs by shop floor staff. You may be losing more customers.