Okay, guys, I'm having a similar issue - also with a Samsung Galaxy S3. To make a long story short, I have uninstalled Avast Anti-Theft (and checked and double-checked and had friends check to make sure I'm not pulling a stooge and installed something else instead). Also, BEFORE I uninstalled Avast Anti-Theft, I removed one person's phone number from the list of people to text in case of a SIM card change. I had three people listed, then I removed one so that only two people were listed, then I deleted the app.
However, all three people are STILL getting texts from my phone every single time I restart it.
I don't know if your server in Prague is getting texts, because I've uninstalled the app so I can no longer open the app to see whether the box to text the server is ticked or unticked.
I do still have Avast Mobile Security installed, but that program shouldn't be texting anyone, right?
Also, just to be sure, I have seen the text messages on two of the three phones in question (the third person called me, but I haven't been able to physically see her phone yet), and it is the message that I programmed into the app, and so on and so forth.
Thanks for your time.