How dare they?

Unbelievable. Telkom just rocks up at my business premises, a franchise restaurant, out of the blue to install fibre. In the process they change my business telephone number, a number the business has had for over 25 years without any warning. How dare they? I am now lumped with all the costs of changing the business number associated with marketing the business, losing my take out customers that don't know the new number etc. Disgusting behaviour from this telecommunications company.