Block SMS from a Name rather than a Number

Somehow my number has been put on a SPAM list and im getting daily SMS from blocked numbers. These appear as random names (such as Lily, Vanessa, etc..) and advertsie random gambling sites. I have never bee non any gambling sites, so this is unsolicited SPAM.

Does anyone know a way of blocking these SMS when there is no number? I have tried enabling the unknown senders on the iphone, but as they dont come from a number, they do not get filtered and come into the Contacts & SMS rather than the Unknown Senders.

I have tried contacting O2, but they cannot help. Anyone ever had this ,and found a way to block such messages??