How/where to complain landlord? She owes me money how and where should I complain to

[Kikkoman]

make her pay me? Hi, I moved out of my previous apartment for a few months now. The landlord asked me to be responsible for one of the utilities of the house. I had to move out early and so I asked the landlord to collect the utilities from the other tenants for me and she readily agreed. I asked her to mail me the money she collected from the other tenants and after two weeks I still haven't receive this cheque so now she is asking me to pay half of the fee to "stop this cheque" so she can write me a new one. I told her that I refuse because I do not know if she mailed the cheque in the first place or not (in her initial emails she did not seem sure that if she REALLY mailed it or if it was the correct address) and I also told her she should have tracked such an important letter. Question is, if she refuses to pay/cooperate, where should I threaten to complain to in order for her to pay me back my money? I live in waterloo, ontario canada if it helps.
I already paid a lot of extra fee for her but I never complained. I had to pay extra util fee for changing the account name when I first moved in. I also had to pay her water heater rent which I did not believe I had to pay. I also moved out early when she told me if I did the next tenant can pay some money because he would be moving in a bit extra early. Later she tells me that the person never moved in so I'm not entitled that money when I asked for my money. I find it very appalling that there's such people exist and I'm just a student... why is she trying to con me my money? I don't even have any!

[duwbryd]

The only thing you can do is sue in small claims court.