Open Question: I am a landlord who has a tenant who will not move out. What can I do? HELP!?

I have had the same tenant living in a single family house for 2.5 years. They had a written lease each of the 1st two years. Recently they are only month-to-month (legal by AZ law). I raised the rent on them with 50 days written notice in December. They sent a letter back to me stating they would move out by March 1st. I have been on the phone with them every few days for the past two weeks asking if they will be out on schedule as agreed. They have assured me and now they are just stalling for more and more time! Aparently they are trying to close on buying a home and now they are having problems and won't move out as agreed. They have not paid anything for March, yet, and I don't want to extend any terms for them either. I have already re-rented the property for March 15th!!! Can I get an injunction and get them out of there or do I have to do a whole eviction??? How long is this going to take? Anyone with advice or if you know how to help, I would most appreciate it!!!