A bit of a long story but I'll try to make it short. My partner and I bought a Nissan Navara from our "friends" through a verbal agreement for $6000.00. We have paid $5000.00. He signed a receipt to state we bought it for $1000.00 (wrong, yes, but it's still a document) and every time we gave them money we wrote it down in a book and got them to sign next to the payment (no dates, though). He informed us there were no issues with the car and it would pass a pink slip easy. My partner booked it in but had to turn around and come home as the rear diff was making noise. My partner removed the rear diff and all the teeth in the centre bearing are chipped and the rear struts are bent. My Dad bought us a new diff for it which we are in the middle of getting put in. Now these so called friends are demanding the car back without returning the money and denying the damage found saying we have done it to the car, which had only been out the front of the house, then moved to the backyard and briefly on the road roughly 5ks. They have even started telling everyone and posting on Facebook that we have stolen the car off them. Can anyone tell me where do we stand under Australian Consumer Law? We don't need their drama for our family. Thanks.