Gas boiler/fire flue
 

I am having real problems sourcing aluminium twin wall flue for a gas
fire. I need to replace one 135 degree elbow that has a split in it.
The annoying thing is that I could do this in the old cement/asbestos??
type flue but I gather you can't get that any more.
How on earth are boilers/fires installed these days if the flue pipe
that is supposed to be available isn't.
Any idea where I might find this in Herts or London. It isn't as if I
am out in the sticks anywhere.

Kevin