Spam sms on Telkom line

I constantly receive an sms on my residential landline to please contact *** regarding a sim change, phone might be ******. My cell phone has not been ****** or lost. The message keeps on coming through 3 to 4 times after I have arrived home from work so I dont know how many times does it ring during the day. It can be any time during the day/night and as I dont have caller ID on my landline it makes it difficult to avoid the call, I can also not see the number it comes from. This has been going on since 1 Aug. I have contacted Telkom 10210 and was put through to the technical dept, waited almost 25 minutes to speak to an agent. He said I must try #65# or #66# during the message. IT DOES NOT WORK. <br> <br>