True, but he just said reduce his monthly instalments, not get rid of them completely. Even without car repayments at all that puts him on R5,800. That's going to make it hard to qualify for any sort of meaningful bond from the bank unless he has a massive deposit, in which case he can just use some of that as a lump sum on the car. And then there are the costs associated with a house beyond the bond (water and lights, rates, life insurance etc. etc.)
@ OP - Note I'm not trying to knock your idea of buying a house, I just want you to know that your house budget is on the seriously low side, so if the only reason you want to change cars is to work with a R5,800 (or less) budget you'd probably be better off saving elsewhere.