Mtn
Spam sms's involving my cell number

I am receiving hundreds of calls per day from people who have received an sms telling them to phone my cell number to receive a prize. I have not being answering my phone, so now am receiving very abusive voice messages telling me to stop sending them sms's. I asked MTN what to do but they said they cant do anything about it. They do not know what number is sending the sms's.