STOP texts aren’t honoured by spam/scammers and can be used to stick you on the confirmed active number list.
Many phones have a facility to block a number, so you can try that.
Sadly there’s no TPS for text messages (though I recommend registering with TPS anyway), but the messages are illegal if you have not requested them so report them via ICO https://ico.org.uk/concerns/marketing/spam-texts/
(noting that usually companies argue that you have given permission at some point in the deep dark past because you did or didn’t tick a relevant box. Usually BS).
And yes, some operators have a text reporting facility as mentioned above. I think you basically forward the text to a particular number to report them.