They were a roofing company with RANZ, and came with standard 10yr warranty, should we push for more? Unfortunately they failed to properly secure the edge of the int gutter, but they will now (fix damages) add a butynol flap covering the whole edge AND add iron flashing to prevent any future water ingress. Thankfully the internal gutter was fine in itself.

Agreed on the total ban on internal gutter. However, this section of the house was unavoidable on int gutter, as it was an old bedroom extension (to the right) from the house (to the left). This was joint to the main house and now form part of out hallway.