Block SMS without number
Since you told DND doesn't block these kind of messages, you can use Textra SMS from the Play Store and select the message that you received and select the Blacklist message option to stop receiving the SMS.

If you still want those messages to be received but not to get a notification you can select the Crossed Bell icon at the top to not notify on receiving the message so that it is stored into your inbox for future use but will not be notified to you.

Update:

Using textra I found another feature to find out the number of those LM-* ,TM-* , VK-* series kinda SMS messages. Open Textra and swipe the message to left to reveal the call feature. Double tap the call button and it calls the number. So now you've got the number and this way you can block those numbers from receving those text messages. I tried that and showed the numbers to me for every message in my inbox with XX-* sms messages. ;)