Bad service

On the 23/12/19 I went to my nearest shoprite branch in the oval centre at around 6:45pm I went in to get a few of my needs and most important my child's formula when I went to the shelf there was no lactogen 3 I then asked for assistance by the admin manager who is khanyisile hlatshwayo she said she will go check on the shelf where I checked while I was waiting another staff member reffered to as maphumu asked me if I needed help I told her I was already being assisted with the formula she then told me the stock rooms were locked as the merchandisers lock the stock rooms at 5 when leaving the store. Khanyisile then came back and met vincent mdluli she then asked him about the formula as there was nothing on the shelf without checking he then said its finished. My question is how did he know without checking besides that the stockroom was locked is it even possible for a stockroom to be locked while the store is even open??? And to conclude on my visit this morning at around 08:30 to shoprite when going into the formula isle I noticed one tin on the shelf so where did this magically come from? I am very disappointed with the service I am a regular customer and always support this store but I can't tolerate it if people dont know how to do their job... And I'm glad that I got excellent service at checkers