[cupcakecalamity]

I live in BC, Canada.
My boyfriend, myself, and our two roommates all signed a 6 month lease on September 15th.
On December 30th, one roommate took off, and never came back. All his stuff remains at the house. He refused to pay for January, so we managed to replace him for February, though he still owes 400$ for January.
The other roommate left around January 15th, just took all his stuff and took off. We told him that he legally had to continue paying unless we replaced him, but he refuses. We could not replace him in time, as he gave zero notice. We had thought we found someone to maybe move in, but that never worked out. So he owes for February.
They are both refusing to speak with us, and so we cannot get in touch with them, as we don't have their phone numbers, or know where they're staying now.
I spoke to the Landlord Tenancy Act, who told me that only our Landlords could go after them legally. The landlords spoke to them, and were told only my boyfriend and I could go after them legally.
The landlords then came over and asked us to get them the 800$ owed, by February 15th, or that would be our 1 month notice, as our lease is up anyway on March 15th.
My boyfriends job recently closed with no notice, and also hadn't paid him his last 2 paychecks. I have been unemployed and searching for 2 years. We do not have the money to pay for what our other roommates owe.
While we are trying to find a second roommate to move in for February 15th, as their half-months rent, and damage deposit, will cover 400$ of the 800$ owed, and we will have to borrow the extra 400$ from someone, we are unsure of how to proceed legally against our two ex-roommates.
Does anyone know the steps I am to take? Or how much its going to cost me to get legal help in going after them?