Experts and BHG readers answer.
brown root spots
Based on your description, it sounds like you already know what the problem is -- mowing too low. It is well understood that lawns thrive when mowed higher, and struggle when mowed short. You are, through your association dues, paying for this service, so I guess this is really between you and your association. There is no shortage of knowledgeable lawn servicers and your association could, if convinced, simply tell the lawn care provider to raise the mowing height, or they'll find another provider. Just remember, most commercial servicers are hired because they offered the lowest bid, not because they are the most competent. And in all things, you get what you pay for, which explains your current predicament, but also why you may get resistance to the idea upping the quality (and also the price, in all likelihood) of your lawn service.