That type of text is called "short code" https://community.republicwireless.com/thread/1637 and although you may but not in all cases be able to receive texts from 411247 but you will NOT be able to reply to that short code so your text to stop is not being received on their end. For example, I can't even receive texts from Redbox for free movie rentals, or i can receive texts from bank for daily balance but can't send to them to get other things. As for unwanted texts https://community.republicwireless.com/thread/2978 this was helpful.
Republic Wireless currently does not support short codes. If you signed up for text alerts when your service was with a different carrier, you will likely continue to receive alerts. However, you will not be able to respond to them. Therefore, your "STOP" request is not being sent to Chick-Fil-A.
Since RW does not currently support sms short codes, you may want to consider a free application to block unwanted calls/text messages. You can find more information in this thread:
all RW phones have 2 phones numbers associated with it, the number you were assigned by RW and a "hidden" mobile phone number.
So the text you are getting is probably being sent to the previous owner of that recycled number
There have been many conversations you can search and find here in the community, here is just one below