Have a look at what your by-laws say right now. If it says you can only have a pet with EC permission then I think the EC would have a very hard time convincing the CTTT that they were now denying you permission that you first requested a year ago.
I also think they need to tell the rentals manager to pull his head in. If he is purely in charge of the letting side of the building he has no right to approach you and tell you to do anything.
Unless your dog is causing any kind of a nuisance, I think you are on safe ground and you should just keep copies of the original communication you had with the EC and wait for them to come after you (if they ever do).