Bit of an update, I now have Easter Monday off. I didn't actually speak to her I was just talking to another colleague about what we were working over Easter etc, I wasn't really moaning, just saying in passing "I'm working both bank holidays and it sucks" kind of thing and didn't think much of it. Anyway he went and told my manager and she pulled me up on it implying that I'd been spreading it around or something when I haven't, I hadn't even mentioned it to anyone at work until today
She said because I'm a 'new colleague' (been there since October, not sure how long I'm classed as new for?) that I have to work any bank holidays they put me down for! So by that point I was thinking "oh well guess I'm gonna be working them then" then she went back on that and said she'd have a look and see if I can have one of the days off and took me off the Monday. Bit confused as to why she would do that when I apparently have to work them if I'm on the rota but I'm not complaining

guess she was just doing me a favour, I didn't protest what she said about new colleagues or anything I was just like "ok". Definitely agree with you though, asda treat their staff like crap, when I first started they were making out like colleagues get this that and the other and I was thinking "this should be a nice Place to work" but then you find out about all the rules which give us no leaway what so ever lol. Oh well at least I've gotten one bank holiday off. Been made to feel guilty about it but I'm sure I'll get over it.
Edit: and I spoke to one of my colleagues who's been working at the store for years about the asking to leave when my shift is over thing and she said that no ones ever had to do that and basically said my manager made it up and that she should be aware of what time staff are due to leave anyway, she basically said that she completely made it up. So I'm not going to follow up with her ridiculous request and if she pulls me up on it I'll tell her that I've never seen anyone else have to do that and why was I not informed of this 'rule' when I first started working there. Tbh I feel somewhat victimised over it but I'm not gonna do anything about it, however i'm going to remember it just in case anything else happens in the future which makes me feel singled out iykwim.