Went to Derby Kingsway retail park on 18 August, 2022 at 5.45pm. We were asked to go to the new self checkout point even though we were almost the next to be served at the normal till. The lady who was in charge of the self checkout tills seems to be a bit bossy and thought we don't know how to operate the simple self checkout machine. After scanning all the items, we pressed next screen which we still can scan my sparks card as I used it in other branches before but this lady kept saying that we were wrong next to my ear and pressed our screen to go back to scan our sparks card first. We found that this worker is so annoying, not well trained and had no basic sense of serving customers. If we do have problems, we will ask for help, if we do not having any problems, don't keep on telling us what we should do. I think the manager of this branch should make sure that their staff are all well trained and carefully monitored their staff performance all the time.