If a tenant doesn't want to pay,(from what I can see and I'm open to correction) there is no legal way (that works)to get them to pay. You can only take them to the PRTB, if you win that, then YOU have to take the tenant to court (you pay those costs) and they won't send someone to jail who has no money. Once you get a court judgement the tenant will probably leave before the bailiffs arrive. That could take 6 months or even a year going by the decisions on the PRTB site. Which you should read. Illegal evictions and over staying/non payment of rent are the ones to read. You as the landlord can have to follow the law exactly or you can be fined heavily. So you need to give the correct notice and then not invalidate it, for example by excepting part payments afterwards.Things like that. I don't know the details, but you'd wise to check them out.
All that considered you would be wise to strike some deal to get them to leave. IMO. Of course by suggesting it, they may see you as a soft touch and dig their heels in. Catch 22.
Maybe theres some honest mistake, and they pay up and you'll have no further problems.