Our tenants are a major PITA to put it mildly.  Among many other things they do, whenever a service contractor comes to the house that we pay for (repairs, landscaping, pool, etc) they always have them do extra things or they have them return to the house because something they did isn't up to their extremely high standards.  For example, last week our landscaper came to trim the tall trees on the property.  Once he was finished, the tenant sent me pictures saying how nice it looked.  Yet, the next day they called him back because they found that there was a 12" clearance from the bottom of one of the trees to the ground, but a 6" clearance from the bottom of another tree to the ground and they wanted it fixed.  Unfortunately the landscaper is too nice to say no so he went and did it for them.  They also told him for next time he needs to make the tops of some really high (>20' high) trees perfectly horizontal.  Obviously this would be difficult and very time consuming so the landscaper wants to charge us more.

We emailed the tenants and told them they were out of line doing that since we pay for the service. It is up to us to dictate what is acceptable.  The tenants responded with a bunch of justifications (and zero apology of course), saying that they are meticulous because they want to keep our property in good condition.  

Problem is this happens every single time someone goes to the house that they are not paying for.  I'm guessing the thing to do is put it in writing every time with the contractor that they are only authorized to do the work we specify and anything else would be the tenants responsibility and they will be at risk of not getting paid for that work.  It seems silly to have to go to these lengths but I guess it is what it is.  The tenants always ignore us when we ask them not to do these things so I'm sure they will do it again in the future.  If they happen to and we get end up getting charged, can we take it out of their security deposit?  Should we send an email saying that anytime they do something like that we will deduct it from the deposit and would that hold up in court (god forbid it actually goes that far!).  Advice?