I'd suggest you post this question on the Trees forum.

Here is a link that might be useful: Trees forum

I have an old fashioned type, the one with 6' sections that can be added as required. The original one's were of wood construction, but the later one's were made of fiberglass.
Some were damaged in a fire about 5 years ago and I went searching for replacements and finally found one company that sold them. Having more pressing priorities, I delayed ordering them. I later found that they were no longer available and only found the type with the sliding extension. The longest one I found was only 21' and I purchased it. Also bought 2 different "chainsaw's on a stick". None would do the job my old antique could, so I repaired it by cutting off the damaged part and remounting the connectors. Saw an ad for a Japanese-made super sharp blade that would replace my old ones, but it is also gathering dust, because it had no "set" and the kerf was so narrow that the blade would become pinched on large diameter limbs. It also was not as sharp as the old blades and only cut on the forward stroke.
You might try finding something suitable on ebay. I didn't check, as I no longer go there, after a prolonged run-in with the idiots that staff it, who assigned my account to someone in another state and then accused me of hijacking it when I corrected their error. I also found it was a rich source of Spyware!

Over the years I have tried several different makes of Pole saws. Fiskars is the one I have settled on. Easy to adjust and comes with a very good saw with plenty of 'set'. After two years of a lot of use I ordered a new blade over the Net from the company and it promptly arrived. I have a large garden that covers several acres and is thirty years old so I use a pole saw quite frequently. I'm happy with Fiskers. They make a very good hand hedge clipper also.