As per the title really.

My seat post seems to have fused to my bike frame. I have fully removed the quick release and sprayed a load of wd40 and proper stuff to unseize metal but it just isn’t working!

Worried that I am going to break the saddle while trying to twist it free.

Is it borked? Do I need a new bike!?

What materials are the seatpost and frame?

Same happened to me.
If its a Steel frame, Alu seatpost get a flat head screwdriver and tap the seat tube out a bit, insert some lube and hey presto

This thread might help,

Good ol’ STW to the rescue

APF

Aluminium frame and alloy post.

Will have a look at the ideas on previous thread.

Cheers!