No offence to NBN but....
Why would you even waste your time replying to a punter who only had a 15 min punt?. Hes not in the regular category and when he started with a tenner offer you knew where it was going to lead.
By replying you were fuelling his fucked up ego.
You have been around a long time to understand the occupation and scene.
Get a better phone with a block feature and use it Rather than replying back.
While it wasnt entirely your fault that he was a fuckwit you should have ignored the constant harassment rather than reply.