Please stop sending SMS's Telkom

Telkom sends me two sms's every day (some days 4) with the same message " Mr.*********x, we've noticed that our e-mail with information about your new Unlimited Business DSL (10Mbps) M2M is not getting through to you, please reply with a valid email address. Visit https://tlkm.link/Broadband for more information on your first bill. T's and C's apply. Telkom Team"

I have responded with email addresses, and have also tried responding with the word "STOP", but the sms's continue each day. I have also tried calling their call center, but their agent told me they have no idea who is sending the sms's and therefore do not know how to stop it.

Anyone know how to stop this?