Continuous phone harrassment

For the last two weeks my family's landline keeps getting calls from a Sanlam automated number - ********** 003. The calls start coming through at around 7am and continue throughout the day. When answering the phone, there is nobody on the other line and the call gets cut. On the odd occassion, however, a voice is heard on the other side. This, however, does not seem to solve the issue as the person they are trying to contact is out of the country - something that has been thoroughly explained to the Sanlam employee. We have even gone to the extent to provide Sanlam with the updated contact details of the person they are trying to contact yet our landline continues to ring and then hang up on many occasions throughout the day. Continuous phone harassment is starting to get really old very quickly, Sanlam.