Cool, will do! Thanks

Hello Last year, me and my girlfriend joined an X4L gym on a monthly contract basis. We paid the first month on the spot when joining (28th Oct) and shortly after had a bad experience. I went online and saw how bad this place is and we decided to cancel. I wrote down all the things I had to do and when, hoping to avoid this. I sent the cancellation request on 9th Nov online as instructed, saved the 'receipt' and also have the confirmation email that came through a few days later. I allowed the final payment to come out on the 27th Nov and then cancelled the DD on the 28th Nov. That's 48 days before the following payment would have been. I've stuck to the terms, yet here we are. As I mentioned, we both joined. I did everything for us both at the same time. I haven't heard a thing from them, but they are chasing my girlfriend. So far, their demands are 2 months membership plus x2 £25 penalties (sorry, 'admin fees'). Most threads around here are people cancelling DD without letting them know, etc. I can't be bothered to write a letter and post it, considering it's obvious they don't care and will just continue. I just wanted to check, am I OK to bounce their emails and forget about it? I know they have no powers... Or, shall I send a letter with the dates in, anything else?