I don't know if the S2x has it but on my Note 2 I have spam blockers. Go to your messaging site app & press menu, then settings & right at the bottom there is # blocking. It has it in the dialer also for calls. If not you can download an app like Comodo Antivirus & it has blockers in it. It's a free app.
If it's coming through the talk app on the phone you get an option to block this person when you tap on the chat request. I've started getting the same requests in the last couple of days, both on my tablet and my phone. Looks like someone has found a new way to bother people.