I spoke to a city inspector yesterday, and I asked him who do tenants contact regarding pests.
He told me to contact the following numbers:
If anyone is experiencing any issues with Bed Bugs, please contact Toronto Health Connection at 416-338-7600.
For all other pests, (Mice, Cockroaches, Rats...etc) , please contact 311 and ask for a property standards officer or you can also email them directly 311@toronto.ca. This way you can keep it on record.