How can I unblock sms on MarshMallow?

[AC Question]

Hi,

I've basically done exactly what this post has done -http://forums.androidcentral.com/ask-question/499516-how-can-i-unblock-sms.html

I attempted to send a message to 40127, which belongs to Vodafone UK. A pop up appeared telling me that the number might cost me a premium. I pressed 'Don't show this again', but it wouldn't allow me send the message. The phone tells me that it's failed sending the message as soon as i press the send button.

I assume that somehow, my handset has blocked the number. How do i unblock the number? Or premium numbers in general?

I attempted to do what was suggested in the post i linked to but the options wasn't available, so i assume it's for another version of Android.

I'm using a Samsung Galaxy S5, on MarshMallow 6.0.1.

Thanks
Bobby