I discovered same today - I was being charged £4.50 a time for a premium rate text received each week (from a different 7000nnnn number). I had just been deleting the texts as they were obvious SPAM. Did not realise they incurred charges until I saw my bill.
I called Virgin Mobile and they were able to tell me the name of the company sending the texts (Global Awareness Ltd via Zamano Ltd) and the number to text STOP to unsubscribe from this "service" I had apparently signed up to (but I hadn't).
I phoned the company and asked them to ensure I received no more texts, to refund the charges already made, and to tell me how I was supposed to have agreed to this in the first place. They said I had "activated the service from my phone" - apparently by accidentally clicking on a banner on a website. At no time was I told that I had incurred any charges.
Now waiting to see that the texts have stopped, and whether I receive the promised refund.
P.S. Virgin Mobile can block you from sending Premium messages but they can't block you from receiving them (nor can my phone do that)
, Ive had 3 premium texts March 2017 from Mgage at £4.50 each, Virgin have suggested texting STOPALL to 85450 to prevent future texts but cant do anything bout the bill, they suggest I phone MGAGE to get the charges cancelled would've thought they could have deleted these charges as I didn't consciously sign up to any MGAGE services and it is not good that this scam (ish) is still being allowed.