harrased and annoyed

I am receiving continues sms and really non custermer friendly calls in work hours insisting that I owe an outstanding amount to Vumatel , I signed up a package with Afri Host ( Thank goodness) and Vumatel is not understanding that this was part of my package , I have sent numerous emails to their complaints desk , spoken to the accounts associates who have confirmed via email and telephonically this would be sorted , yet internally this has not been.

please can these calls stop as it feels like I am being harassed now!!