Vodacom fibre line

Good day We have been speaking to vodacom a few times today.. Gave them a VT number so they could cancel previous owners internet line from vodacom. As we have installed fibre from Vumatel and went through Vox but Vox cant move forward with our internet line as there is still an old vodacom line and this house was brought on auction so nobody knows the previous owners so we cant get hold of them to cancel it. Please can you kindly assist us as we have been waiting for 3 weeks now.