Its in our lease when you put in a maintenance request it gives permission to enter. All maintenance has to be in some form of writing(email, note left at the office, text) unless its an emergency. Nine times out of ten if they all of a sudden want appointments made and this is not the usual practice they are hiding something(unauthorized pet, occupant, condition of the unit, drug use something of that nature). Usually when tenants are demanding the office works around their schedule its a red flag for something somewhere. Explain to them this slows the progress down and because of that maintenance cannot make appointments for requests, usually they will slip up and give you some type of hint to whats going on when they fuss about it. When my residents start demanding things like this i sometimes send out a quick memo reminding them of the pet policy, occupant policy, no drug tolerance policy, maintenance request policy etc. Make it sound like i already know the offenders but giving them a chance to make it right before i take action and some of them will either ask questions that clue into what they are up to and what needs to be watched for or will start the process to clean up the hidden issue. We only allow appointments for things like this on a very minimal basis ( for example an older lady who lives by herself and moved to the complex because her previous unit was broken into and is now skeptical of everyone and everything) even then its not an appointment set just a notice that lets her know on such and such day someone will be entering your unit to work on your request.