Your question is rather interesting.
For clarification about your case :
(1) You had completed your tenancy contract and Landlord is still withholding your security deposit. Right?
(2) When is the unit being hand over? Or you are still staying in the unit, for whatever reason.
(3) Did you engage a salesperson to assist you when you get into this tenancy agreement? If yes, you might want to try calling him/her and ask for assistance.
(4) When was the "faulty toilet bowl" being discovered?
If you felt you might be taken advantage, I think you can try to approach CASE for help though they might not handle tenancy matters.
Have your facts sorted out and the supporting document ready so the party assisting you would understand the case easily. In worse situation, you might need to file the case to Small Claim Tribunal though no sure if it is worth the time and effort to go through the legal proceeding.
Sometimes, things can be sorted out with a calm discussion and reasonable settlement achieved that is fair to both parties.
Best regards. Read More