Mate diary, write everything down and I mean everything... every phone call, every email etc... you CAN NOT document enough... there is never enough documentation.
Photograph everything... get a written report from a jeep dealership and from someone else, maybe RAC car inspections... then write a letter to the jeep dealership esplaining everything with the evidence... if no go then YES you need to goto DOCEP (consumer affairs)
www.docep.wa.gov.au or is it
www.docep.gov.au anyhow they will also want lots of proof that you have tried to get the issue fixed... they will also ask you to write a letter to the delaership first... but the minute you mention DOCEP or Consumer affiars its likely to get ugly... so be prepared. go down the path of being nice, write the letter and then goto docep... they are there to help you.
But as Crazy nuts said... registered post
Cheers