Aaaggh I am SO with you right now!

DD is saying Oh F***! and What the hell? All the time. I too am mortified.
We have been ignoring for weeks now and it isn't working, she'll stop for a few days like she's forgotten and then just start it up again. I'm taking her to my mum's today for a few days and I just know she's going to let fly there, my mother will clip ME around the ear! LOL.
I don't know what to do so will be watching to see if there's some advice here for us as well.
Just know you are not alone