How best to join different size guttering?

[Quid_Nunc]

Neighbour has built an extension and replaced his roof guttering (see below). It leaks at the join, which is a few inches on our side from the party wall. The new guttering (on the right) is a different design/size. And the downpipe should be further in to his side, based on the approved plans.

How can this best be fixed so that the guttering does not leak when it rains? The water falls on to our patio.

 

[catlad]

If you don't want to tell the neighbour then a hopper and a branch should do it.

 

[Harry Bloomfield]

How can this best be fixed so that the guttering does not leak when it rains? The water falls on to our patio.

You have my sympathy. We had new guttering, which perfectly mated with next door's system. They then had a cowboy company in, installing sophits, fascias and gutters, with the result that out recent new gutters no longer matched or sealed, so we had water running down our wall. They refused to call the installer back. I decided the best solution was to simply install sophits, fascias, and gutters to match it all up.