Supervisors are too busy - Retail Operative Primark Employee Review

Not organised, supervisors are rubbish, was never informed of overtime opportunities. Once spent a good five minutes explaining to a customer that she couldn't return the socks she'd bought because she'd worn them (they were literally brown/yellow on the bottom where she'd been walking around her house in them, and no, she hadn't bothered to at least wash them first) in the end I called my supervisor over in the hope the customer would listen to someone with more 'authority' my supervisor couldn't be bothered to deal with it and just told me to return them. Embarrassing me in front of colleagues and customers who had just seen me insisting I couldn't return them. And I was in the right not to. You should not be able to return clothes that you have worn unless they are faulty! I was also once told I had to be on tills but also clear the back of the tills (where customers unwanted items get dumped) I was the only member of staff on the section that morning other than my supervisor that told me to do this, I was returning the items from behind the till to the shop floor and when I returned to the tills there was a customer waiting (bearing in mind this was about 3 minutes after we had opened) my supervisor was standing by the tills (not serving the customer) but waiting for me to return so that she could shout (literally shout at me like a was a school kid) that I wasn't allowed to leave the tills and that the customer had been waiting and asked me what I thought I was doing just wondering off when I was the only one on tills. She did this in front of the customer who I'm sure would have rather been served than me my getting told off. I don't know why the supervisor told me to do two tasks that cannot be done simultaneously but expect me to do them simultaneously, I suspect she felt she was above serving customers as she decided to wait for me to return rather than serve the customer. And she had a very bad idea of how to deal with an employee making a mistake. (I presume that she had intended for me to stop clearing the back and stay on tills when the store opened, but I was under the impression that I needed to clear the whole thing). 'BENEFITS' NO STAFF DISCOUNT (not that it would save you much anyway) when I got hired they gave us a booklet full of these companies that we supposedly got discount at, guy doing the induction said how good they were cause the company was making up for no staff discount. You had to phone numbers to get codes for the discount...I tried using one for the cinema, the robot voice on the phone said the offer was no longer in use. I then tried a few others out of curiosity..none of them worked apart from one that was something to do with £10 off some insurance (??!!) I also once got called to the office for a disciplinary because they messed up my holiday rota and had it down that I had just not showed up for 3 weeks. Also got told off like a school kid once because I was apparently putting out a delivery of socks too slowly (I had never been trained on how to put the stock out and it was the sock section by the tills and was an absolute mess...it's hard to put out a delivery when they rails are such a state.)