External Water Leak

Hi,
Aplologies as I don't know exactly where to post this so hopefully this is an appropriate place.

My neighbour has a leak under his driveway which started as a small puddle, but has developed into something bigger and now flooding part of our new bloc paved driveway which was only laid in June.

Essex & Suffolk water have been round and said the leak is inside my neighbours boundary and issued him with a 30 day notice to fix.
Less than two years ago he had another leak not far from where the water is now, but they fixed that one. They did say at the time the next time he reports one it will cost him as this was a "free" one.

I am brought into this as it is a shared water supply pipe, but the neighbour is unaware of this as was I until yesterday. Reading material it appears I find myself liable to pay half the repair costs which I imagine will be over a thousand pounds.

My neighbour found a company who will do the work over the Bank Holiday weekend, so just over a week away.

I am trying to research and find out information on this subject as I am sure many do when faced with something they don't know about or the unknown.

Questions I have but haven't contacted anyone about yet.
If I am on a shared supply, can I use my "free" repair card although its under my neighbours driveway.
Neighbour had a similar problem close by less than two years ago. What about a guarantee from the free repair.
Could contact my insurance. Its a bit vague if I am covered or not.
Read an article where someone claimed on accidental damage. They said supply pipes do not wear out, they only leak when ground is disturbed by movement, tree roots, traffic vibration. Conincidentally there is damage in the road right next to the leak. When certain traffic goes over this it causes furniture and noises inside our houses such is the seismic activity sent out.

I am hoping there is something here I have written which someone can say I should investigate or pursue which might help us or neighbour financially as we find ourselves in this situation.
Thanks.