Hi
My advice is not to torture yourself about it, we rent flats in Belfast and many many times we have been stroked for similar amountsd and more.
Yes you can chase it and get all annoyed over it etc etc but very seldom do you ever get anywhere and you end up nearly getting to the stage where you would pay £50 not to have the worry & anxiety & sleepless nights.
Put it down to experience, you may even be lucky some day and have the smug satisfaction that she needs you again someday and you will be able to tell her to get lost.
230K
I also rent out a flat. I hate people taking the pi*s and getting away without paying their way in life.
However, having taken people to court in the last year or so and still getting nothing other than extra fees I've had to pay for court/baliffs, etc, I am still worse off.
Although it still winds me up (I'm currently chasing British Gas for an £8 debt the last tenant left on the meter), sometimes for all the effort I wonder if I should take a deep breath, stand back & write it off to experience. File it in the "one day I hope to get revenge" folder.