Has anyone had any experience of this? Is it easy to do/fairly efficient?

I've just realized I've had £180 taken from my account which, given that I'm unemployed, I really can't afford to lose. Obviously, I've cancelled my card and I'm getting the forms through the post but how long do these things generally take to reclaim?

On a side note, am I missing something here or does ordering home delivery groceries using someone else's card details make you really, really easy to trace? Was this person just relying on me not noticing the 125 quid s/he spent magically disappearing out of my account?