I keep getting SMS spam from Three mobile and I'm looking for a way to block it. The problem is that the SMSes don't come from a regular number, it just says "From Three" but there's no associated phone number.
According to Ofcom I should be able to reply "STOP" but there's no reply option for this type of special SMSes.
Is there any way to block this type of spam?
(I'm on Android 6.0.1, Xperia Z5)