I have parental controls disabled on my account (I'm 41 years old so I trust myself!) yet I still find I can't access certain sites and the page that comes up tells me to disable parental controls to access it!
Its a glitch at VM end, a phone call can sort it, or change the settings in your account online to the opposite setting from what it is now and wait a good 20mins then if it does not work change it back and it may work.
I ended up with access to all sites though it was set to block but now its working for me set to correct settings and I am not touching it again just to be safe.
I never did mess with it, I assume VM blocked it be default when they revamped site.