Tenant changed the locks, but sent us the keys?

[Vida Dillard]

A tenant recently locked himself out of his apartment (for the 2nd time).  He wanted to avoid paying the fee for us to drive out to his apartment and let him in, so he changed the locks and mailed us the new keys.  Its very clearly written in the lease that the tenant cannot change the locks without written permission from the Landlord.  We don't want to evict him, but not sure how to react.  I sent him a formal notice that he had broken his lease.  

I now need to make sure the keys he sent me are really for his apartment, and track down the maintenance guy to give him a new set.  

I'm a pretty new property manager/owner, and just wondering if anyone has had a similar situation and how you handled it.  

thanks,

Vida