A complaint isn't really a request, even though the complainer usually expects some action to be taken in response to it.
You can write something like this: Some of the most common communications our hotel receives from guests are complaints about issues like broken fans, faulty light switches, or failing air conditioning.
I put the air conditioning issue last because it seemed more natural to list them in approximate order of severity. I used the plural for fans and switches because the hotel contains more than one of each. If each room had its own air conditioner, I could have written ...or failing air conditioners.
Student or Learner