I see: its epoxy bonded carbon fiber tubes in aluminum junctions, and the Aluminum seat post clamping ears cracked ..

repairs will be really expensive and may even be impossible without access to more of the Carbon Fiber Tubes
since you May have to cut one to begin to take the seat cluster apart

IDK if they Copied the 'screwed and glued' Italian AlAn frames or Not .. Those, the "lugs" and the Tubes were threaded

RH on one end LH on the Other so turning the Tube around Pulled it's end pieces into the final position ,
then the Epoxy Cured .

Had An AlAn , found Air Freight to & from Italy was Really Expensive But once there the replacement cost was not huge.

But including Shipping It was , so that frame was Retired..


File what is left smooth then make a seat post that will expand , like a Quill handle bar stem. inside the seat tube.

You may have to Hire a Machinist and their shop time to get that..

Or just Fix your saddle Height where you want It, and epoxy the seat Post in Place

with the bolt (or set screw) thru the seat tube and the seat post to make sure it wont Move, as Suggested above..