They lie about refunding your travel expenses: they won't refund them.
They lie about holidays: you'll find it difficult to get them to agree your holiday dates.
They take money from your pay without explanation.
They won't pay your last week's pay.
They call your phone at any time they feel like.
You can travel to work and find that they've assigned someone else there without telling you.
Training is not sufficient to make Guards aware of the service some of their customers require.
Tesco sites can regard you as a pin-cushion. I was told , several times that I was there to physically tangle with the scum who steal.
I once was told that I should take over a store where a guard "had got a splinter in his leg". When I got there, it turned out he was in hospital, having been stabbed the day before.