canceled sly about 3 months ago they keep sending me a bill for 66 euro they say there going to send it to a debt collectors agency and says it can affect my credit rating in the future and can lead to legal action been brought against me are they bluffing or for real
they just keep sending you letters, then a debt collector company will send letters, don't respond, they do nothing in the end. only banks can report to credit rating, like if you don't pay a loan or credit card, so no worries there.
Yes they can blacklist you. They don't do it themselves, they (or the debt collector) would take legal action in the small claims court to recover the debt, thus the small claims court would issue a CCJ) Do not ignore them. If you have cancelled you need to chase them up. Send all letters recorded delivery and only deal in writing and not telephone. Keep a copy of all letters sent.