you HAVE to do this.
do butts girlie. you HAVE to HAVE to do this.
today if possible. even if you ring them and let them know. then you can make a proper report at the cop shop later.
apart from anything, he could have made a counter claim that you crashed into him. witnesses or otherwise, if the nett damage to both cars exceeds $1500, then the driver which caused the accident can be liable for criminal charges.
therefore, you need to go and tell them everything you know. especially seeing as he did a ruinner.
PLUS, because he hit you, if you find that your car is more fuxxed than you think, you will need to have made a police report for any court proceedings OR EVEN INSURANCE CLAIMS.
takes 1 call - do it now. or I'll spank your bottom.