How will they know who i am?

Ok i have just been accused of stealing in Primark i am 16 it was a set-up by my ex friend me and my little sister went and so did she we went to shop however the other girl decided to steal and i had a bag on my back while i wasn't looking she stored the goods in my bag and my little sister saw and couldn't warn me before we got out of the store now i have got a criminal record because of this selfish stupid girl, the people who worked there said i am not allowed to go to any Primark Store in the country but what i don't understand is how will they know because there are over a million shoppers everyday and if they have pictures there must be an awful lot of thieves for them to look out for so how will they know who i ma if i go to a different Primark?