is there a local machining shop that does reaming if so go and speak to them and see if they will remove it that way .
A reamer cannot
remove a stuck seat post, you may use a reamer to smooth the inside of the tube when the seatpost has been removed, I will often do this when I'm refurb'ing a frame so the fit of the seatpost is a better interference
As Nob implies a stuck seatpost can be a real problem...Plus Gas, Coca Cola...a long time soak is worth a try before butchery.
Co-founder of a V-CC section, member South Eastern Road Club and owner of - 2005 Bianchi Reparto Corse (modern), 1985 Raleigh SBDU Pro Super, 1984 Raleigh LU Corsa, 1980 Allin Stan Butler Special, 1978 Ron Cooper, 1975 Bill Philbrook tourer, 2 x very early Roberts (mid/late 1960s), 1966 Raleigh Superbe Roadster, 1964 Allin Stan Butler Special Belgique, 1951 Hobbs of Barbican S/C, 1950 Hobbs of Barbican S/C, 1947 Hetchins Super Special, 1908 Centaur Featherweight. 1988 Specialized Stumpjumper.