How do I handle this?!?!

[Jordin Boyd]

Hello!

I hope someone can help me out. I own one rental property and I have a lease option tenant in the house right now. The tenant has a 2 year lease and a separate "option to purchase" agreement. Things were going well until my tenants (husband and wife) both quit their jobs for "better jobs." Since then they have been late with their rent for the past 6 months. Because of their late payments, the contract stipulates a permanent rent hike of $25 for every month they are late from now on. They have paid the extra rent plus late fees a couple of times but this last time they just deposited $1400.00 (with the late fees and two "rent hikes" it should have been $1450.00 and they were well aware of this fact). The tenant just told me, and I quote "$1450 is just too much. We cant do it. So you just get $1400. Thats all we can do." I reminded them that we started with a very reasonable $1400/mo and that they were happy with that when they signed the lease.

What do I do now? Do I demand they pay the extra $50 right away? Next time? What do I do? I don't want them to think they can make the rules. What would you do?