The rating of the crime of robbery depends on if force is used or just the threat of force. If just the threat, it is a class B crime. If actual force is used or if the defendant is armed with a deadly weapon, it is a class A crime. Aggravated criminal trespass is a Class C crime.
Robbery is theft or attempted theft from an individual (versus a car, home, etc) that causes injury, by threat of injury, or by causing fear of injury. Aggravated criminal trespass is the entering onto or remaining on the property of another without their effective consent, causing injury, threatening injury, or causing fear of injury. The latter is the less serious crime of the two.
The police and prosecutors investigate to see if prosecution is the next step.
I think you probably mean a "Trespass to Property" notice. If so, there is no formal method of service.
Denny Ferguson has: Played Night Porter in "Stormy Monday" in 1988. Played Gordon Hewlett in "Spender" in 1991. Played Trepass in "Harry" in 1993. Played Cooper in "Our Friends in the North" in 1996. Played Dapper Man in "The Girl" in 1996. Played Father in "Throwaways" in 1996. Played Clarke in "Badger" in 1999. Played Miner in "Billy Elliot" in 2000.