IMHO
Option 1) Refuse them access when they want to work on it, pretend you are not aware of the hole in your own property in the end no one told you about it. (What if its a scammer pretending to be telkom and then gains access to your property)
Option 2) Use excuses such as you are not at home, the time they can work is inconvenient etc... They must fall into your schedule, you only have a window between 00:00 and 02:00.
Can they just enter your property without your consent ???
Assume the following situation: What if you have a big vicious dog kept safely within your own property having sufficient warning signs on your gate, they then without your permission enter your private property by breaking your fence/gate(Property damage), and the dog rips them to shreds surely not your fault.