Standard Bank - we refuse to take this number of our system!

I have the worst time in the world trying to get Standard Bank to take my work number off their system. The previous employee who had this phone left the company 6 years ago and still since I joined Standard Bank have had the audacity to continue calling and sending sms's. Beggging and pleading for 6 years come on people how difficult can it possibly be to make a note on the system??? The worst is every time they call I request the call centre agent to talk to their supervisor to take this number off. Low and behold 2 minutes later I get an sms from the same person. I will never do business with Standard Bank due to this 6 year battle to get someone else's lack of payments to them resolved.