Welcome to the community and thanks for posting. I'm sorry to hear your parental controls settings are still on.
Follow Gorf's link and steps and you should find parental controls. Turn it off. A green message will appear. You'll need to wait 2-24 hours for this to be successful. I've just tried to login in from my phone and it worked fine.
Sorry to hear you're experiencing problems turning parental controls off. I'd like to help you get this sorted.
There are two ways you can turn parental controls off. Firstly could you log into your mobile account online here please.
Click on plan and device > Click the tab manage services.
Make sure parental controls are set to off here. If it isn't move the slider to off and click update. This will present you with a green success message. It may take up to 24hrs for this to go live on your account.
If this doesn't work out for you please give our mobile team a call on 789 or alternatively 0345 6000 789 so we can get this sorted for you.