Kaspa’s Desserts complaint: Lack of professionalism and communication

I have completed two shifts at kaspas now, my first shift was on a Sunday and was supposed to be my training day. The manager wasn’t in as she is on holiday – the store has only just opened – so I was unable to give my details, proof to work in the UK nor get a clock in code. The supervisor merely wrote down my times on a post it note, I took a picture of this as proof. My second shift the same happened and I felt extremely worried about this, I broke down to the supervisor and she reassured me I would get paid but someones word is not enough, I would be put at ease if my details were taken. I have cried multiple times about this as well as emailing multiple people to get this sorted and every time they just say bare with me. I refused to come into work until this is resolved as currently I feel as though I am working for free.
I don’t know what to do as no one has replied to me or resolved the issue.