Tenant refusing to make rent payment and has vacated property

[Kyle Agius]

Hello,

I had three friends living in a duplex unit in Casper, WY.  In August of last year, they signed a one month lease after requesting just a 9 month lease.  All three have signed with no cosigners.  As I expected, last month, they suddenly needed to vacate after 9 months due to a few sob stories (in reality, they were students and school has just ended).  I have spoken with them and informed them they are still responsible for their rent through the end of August, or until I am able to find a replacement tenant to sign a new lease term, at which point I would be fine with them walking away. 

As of today, June 2nd, two of the three have made their rent payment for the month of June.  The third is non responsive to the other two renters and has not sent any payment.  I have not reached out to her as of yet.  

My question is two parts

1.) She only owes around $350 so I want to take all measures possible to avoid any legal proceedings as its not worth the time and money.  What steps should be taken when reaching out to her to make her feel like she is obligated, but to not break any laws regarding harassment.

2.) If she refuses to pay or ignores, what steps would you guys take without costing myself any time/money/headache to make her feel some of the pressure that i do.  

Thank you!