Does your agreement say anything about trees, for example an obligation on you to prevent them damaging the cable?
It’s ambiguous. It does say under “my responsibilities” that (my translated wording) I must not plant any trees or shrubs likely to cause damage. But not sure how that would apply to existing trees, that were planted before the wayleave was created. Or even to trees that planted themselves.
It also includes a clause that I can ask them to move their stuff if I want to redevelop the land. That bit is wrapped up in lots of legalese that, I think, means my reason for asking must be reasonable.
PS: On closer inspection, it refers to the possibility that the roots might cause damage to underground stuff, rather than the canopy causing damage to overhead wires. But then, my agreement does not include anything overhead, it’s all underground.
Edit - added PS.