@rayofhislight You should be documenting everything (video, photos, sound recordings, including the bites you sustained) and keeping a log of events. Don't leave your house without your phone on video record.
Yes, send a letter to the management, according to the rules for official communication to management in your jurisdiction. For instance where I live, nothing is considered official communication with a landlord unless it is in writing and sent by either confirmed fax or registered mail or hand delivered.
You should also contact animal control where you live and report your bite. The police may notify animal control or they may not. Where I live I must contact animal control even if the police take a report. Give animal control a copy of the police report or the report ID#.
Every owner of a misbehaving dog says what you heard: 'S/He never did that before!" "S/He's always so gentle;" "I don't understand;" etc. It's just defensive posturing and means nothing when you're disinfecting your or your dog's bite wounds, or trying to protect yourself from an aggressive dog.
People are terrible with their dogs these days for a number of reasons, many not deliberate, just ignorant. The owners themselves are excessively anxious about other people and their dogs sense this. They don't train or socialize their pets; many don't walk their dogs ever. They live in small spaces, and their pets lack mental and physical activity. All this leads to anxious reactive dogs.
Irresponsible anxious misbehaving adults often act like children and avoid difficult situations, as you observe with your neighbors. One more reason to take this up with official sources, since the neighbors don't seem capable of handling this like adults.
Source: My mellow friendly old dog has been bitten twice in the past year - while on leash - by other (illegally) unleashed dogs (mis)handled by ignorant owners. Most recently a week ago. The dog's owner, new to our neighborhood from out of state, made the typical excuses, but talking to a few more neighbors, I learned this guy's dog has gone after at least 4 other dogs in the past 3 weeks.
My dog's injuries weren't severe and I decided to handle things between the two of us. I told him that I'd overlook this incident so long as my dog's bites didn't become infected, in which case I'd need to take him to the vet, and the vet would be required to report the bites. And so long as I never saw the dog unleashed ever again for any reason. I suspected the new neighbor hadn't had his dog registered/tagged here (yet), and explained to him that no local tags + bite history means 3 week quarantine at his expense. And I warned the neighbors.