Happily preparing myself for the on coming orientation camp.. but was not selected. So how? continue working lor

Was on leave on monday. Came back on tuesday without expecting the 'new' girl to be already reporting for work. very small size till i appear to be a monster beside her. She is quite a faast learner to me. She ok and almost remember most of the things i teach. Then i realised she reported to work on monday when i was at home, slacking. Tuesday sales order was BADLY lots and got to rush through so didnt guide her well until towards the end of the day.

Quarrelled with a customer on tuesday. He was grumbling about his order not being process. He start to talk unreasonably and raise his voice. I just insist my point through saying that saturday is not a working day and i was on leave on monday, therefore it is not possible to give us 3 lead days plus the warehouse is super packed with deliveries. I also raise my voice. My colleagues were shocked that i can actually scold. I gave him the normal delivery schedule hacking his stand.

Come wednesday, the 'new' girl told me this job is not suitable for her. She wants to leave. Tell me dont pin too much on her. She told the HR about her leave, HR response was do till friday then if still dont like then friday last day. But in the mean time dont tell the rest yet. I dont know what my HR mean by saying that statement.

Thursday, she made her stand, She dont want to work here. Waste my effort and time. Hope the next one will be better:)