Tell them that you will go to land tribunal if no rent is received within 7 days. If they really don't pay you after the deadline, then, you go to land tribunal, they will help you to ask them to leave legally.
If put the case to land tribunal, yes, the whole process will last at least few months time but normally when you put the case to land tribunal, then they will send letter to your 租客 to let them know that the case is now go to court. Usually, they will move out sooner and will not wait until the court's finally decision as you will 100% sure to win the case that's mean they have to pay the court fee and you can get back all the rent they owe you legally, they can't escape even $1.