I would tell then to get stuffed..
1, how did it cost £24,000???? The people that fixed it have to be paid anyway.
2, looks like it is on the homeowners ground. As pointed out, i would be telling them that they have no wayleave agreement, it is trespass to property and get it moved. Further, you try to sue us, and we will counterclaim for the injury and the PTSD...
3, Since it constitutes an actionable nuisance, it prevents them building on their property, you have a right to "self abatement" i would not have let them repair it and told them to shift it.
4, I would get the HSE too..
5, The electric people might try to get a wayleave, but i doubt very much that you can get a retrospective one..
6, Since they have repaired it, i doubt very much that it is now a minimum 1000mm i think it is with HV cables below the garden, it would be HSE time again..
john..