Continuous sms of account in arrears,

I have for the past 3 months been getting sms's that my account is in arrears, I have contacted them 3 times to confirm they have the wrong number as I am in KZN and that I never had an account with them, They confirmed that they where given the wrong number and shall remove my number from there data base, which happened for 1 week and then from there on they have been sending me the sms's, I have emailed them as well to get no reply.D