Oh tell me about it. I used to work in a charity shop and was barred from it by the assistant manager who said when I was browsing that I was in the rear room when I wasn't. I denied it and was basically called a liar (not for the first time), and when I said 'whatever' because I wasn't in a mood physically or mentally for a confrontation I was barred.
And yes, Mick is foolish to trust Janine, there are too many people who know what she's like. If it had been one person you could say it was a personal grudge, but not everyone.