This right here, is a ridiculous thread.
Let me clarify up front, I have never purchased from Slide, so I am in no way biased, but seriously, your order hasn't arrived within a mere 48 hours after it is supposedly sent and you immediately believe you have been ripped off and create this thread to cry wolf? Give them a break and wake up to reality. I personally demand a high standard of service with the businesses I deal with however at the same time I understand that they ARE a business, fielding in some cases huge numbers of enquiries daily and despite best efforts its often just not possible to get back to everyone as quickly as they would like.
Had it been 2 weeks with no response and no parts, perhaps I could have understood you being so concerned, but after 2 days, you have not only jumped the gun, but you have made yourself out to look like the fool after your parts arrived on time, and yet you leave behind a thread sledging Sliding Performance, hardly fair.
Furthermore, as others have said, Australia Post are worthless at the best of times and just because they have not entered a registered post item number into their system within a reasonable time, that in no way reflects on Slide. Hell I order parts for my cars from Japan every other week and I could bitch the same way about EMS, I have tried to track EMS parcels and had them arrive on my doorstep before the tracking information has even appeared in the system.
Bottom line, be patient and next time, approach such a situation in a more appropriate way.