MTN spams their customers

I have been an MTN customer for years. I recently renewed my contract and is now bombarded with SMS messages advertising products and services. I cannot block the messages because MTN is not using a conventional telephone number. Some offers an option to opt out, but that costs ME money! I have not given you permission to contact me with ANY OFFERS Whatsoever. <br> <br> How dare you spam me, a loyal customer!! I have already dissuaded someone from switching from Cell-C to MTN today.<br> <br> And another thing: Put some consultants at the other end of your customer care lines. You are not fooling us with your automated systems and \high call volumes"."""