@Antonia **************************
your extension was NOT officially cancelled and you will NOT be able to get a new Non-B inside the country OR get an extension on a new Non-B you got from another country UNTIL you get that old extension canceled
AND you can (and most likely WILL be fined 500 baht a day from the date you left the country until you cancel the old extension with a max fine of 20K baht).
Remember leaving the country and just stamping out on an extension (especially one based on employment) doesn't officially CANCEL it.