Can anyone offer any supportive advice please
Welcome to the Board. I'm sorry about what has brought you here, but thankful you found us and took the step to post.
One of the things all of us here in our little corner of SR have had to learn is when it comes to a loved one's addiction, we are powerless. Love does not matter. Understanding does not matter. Support does not matter. There is nothing you or your parents can do to get your brother to snap out of it. The only way he will is when
he, and
he alone, decides enough is enough, goes to treatment, and does the necessary and difficult work to remain clean.
Your parents will have to come to this realization on their own schedule. It is a difficult thing, watching your child self destruct in front of your eyes. Some difficult decisions are going to be at their doorstep. For now, however, focus on you. Coming here is a good first step. Read our stories, absorb the lessons from those stories, and see how you can apply them to your situation.
Keep us posted, and again, Welcome to the Board.