When I worked in a bike shop many years ago a customer had a similar problem, but it was a seat post stuck in seat tube.
The only solution was to heat the seat post so it melted - being aluminium with a much lower melting point than the frame it wasn't a problem.
The paintwork was buggered though...
@NeilFairbrother started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
When I worked in a bike shop many years ago a customer had a similar problem, but it was a seat post stuck in seat tube.
The only solution was to heat the seat post so it melted - being aluminium with a much lower melting point than the frame it wasn't a problem.
The paintwork was buggered though...