overcharges (again!!)

I was charged an extra 27EUR last month for "Verbindungen (ohne MwSt.) (Details siehe ggf. Einzelverbindungsnachweis)"



When I download my rechnung, it says 3 of 5 pages, but I cannot see pages 4 and 5!



I asked several months ago for O2 to block any and all ABOs.



How do you contact O2? Chat? Email? Post?? My German is pretty good but understanding on the phone is close to impossible.