I am a fully licensed, qualified, certified, Canadian propane dispensing technician (read: grunt with a valid ticket). If the propane bottle has been re-certified and is within the Canadian mandated 10 year age limit, the cylinder can and should be refilled. If it is within spec, with a readable and recognized re-certification date and the propane dispensary person declines to fill it, get the name of the place, the license number of said dispenser person and file a complaint. The only time I have refused a re-certified propane cylinder is if I couldn't make out the date or if the date was obviously "fudged" together by somebody with a letter and number die set trying to pull a fast one. Also, some re-certification places, in both USA and Canada, just don't give a monkey's butt care about the quality of their date stamp process which results in poor or unreadable dates. I am pretty sure that what you have heard is perhaps hearsay, rumor or just plain old BS.
Cheers!
Mike
PS; nothing wrong with Flame King propane cylinders, we fill those just fine!