Pulling in my experience is not always as easy as just boiling.
Before giving up, should try to setup a pulling setup that you can fully pull against the grip (while it's hot).
If you don't already have something thought up or a dedicated pulling setup, here's my approach:
My DIY suggestion is to use a sturdy full size folding ladder . Lay ladder flat on ground, and close the ladder legs onto the pole shaft, so the grip is fully on other side of the ladder legs.
Now you sit down on the ground, hold the pole in your hands with arms extended and pole pointed between your legs, basically like a rowing machine. In this setup, you can legpress against the ladder which will press out the grip. This will allow you to exert as much as you can legpress, or as much as your arms can hold.
If you want you can also throw your whole body into it and sacrifice a slipped disc for your too long poles. (You have all of summer to recover).
Other method say you can accomplish same setup using the gap in a door hinge if you can get your basket off, but that seems you will likely dent and damage your door.
You can probably easily create some similar pulling setup , but keep with the general idea to get it somehow pincered and use a big enough setup where you can think about utilizing your leg muscles to press it out rather than going with arms.
(heating still necessary and recommended).
As far as poles labelled Composite vs pure carbon, if they aren't advertising pure carbon, I would just assume it to be as plastic, yea just use any fine hacksaw, even the $2 small disposable one in the bargain bin from homedepot.