I had a letter left on my car for parking in front of a house once too.
I wrote back that I would TRY to find other parking spaces, but it's a public street and if nothing else is available I'm not going to park an additional block away if this is the most convenient spot.
I mean, I get that it's frustrating not to have your favorite spot, but if you bought a house without a garage with public street parking as the only option, you need to expect that occasionally people are going to park there if you don't get there first.
I would never buy a house or live in an apartment with street parking as the only parking option. I've had a window smashed in where I used to live, all because I left my $30-40 Target jacket in the front seat and (most stupid on my part) a Nordstrom shoe box on the floor in the back that I was using as a garbage can. Also wasn't an ideal time to realize that my car insurance had a really high deductible and also didn't cover glass damage for free (I'd never been in an accident or used my insurance ever before that). I switched insurance REAL QUICK after that.