Hi Bowdon, sorry to hear you're still having problems.
I'm going to try and put my thoughts down and hopefully they'll make sense. I work for a transport company (workshop manager), and I would say that delivering it on a pallet is probably the best method - I've never seen a courier throw a pallet where we all know normal parcels get chucked around. However it's still going to get a lot of bumps in transit, and this is a very big problem with computers, especially ones which have heavy GPUs, heat sinks and the like, they are likely to move. Water cooling will only further add to the issues, hence why there is internal packaging. Safest method would be to deliver and collect it yourself, which probably isn't practical.
I've read the main parts of the review and looked at the pictures. They seem to have used good quality components, although I'm not familiar with them it's generally a good brand. When I built my system I researched what I used, I had a lot of problems with an Alphacool rad - it was very badly made, so that went back (twice) and in the end I got Hardware Labs rad. The reservoir I had to get from America, and it uses a compression seal on the tube. A lot of tube reservoirs cut a thread onto the tube I believe and that is not as reliable.
A couple of things I noticed, in my opinion and Bit-Tech mentioned it the wiring behind the motherboard is terrible, but as Bit-Tech says it doesn't really matter and it's not seen - I'm a bit OCD when it comes to tidy wiring, and I often think why do I go to such trouble when it wont be seen! The other thing is and this is relevant to your problem, the pipes look like they may be putting stress on the fittings, couple that to a bumpy journey in a truck and that could well cause problems. The reservoir also looks pulled to a slight angle, bear in mind that this is a PC built and sent in for review so more care may well have been taken than when they built you're PC.
Given the repeated faults you've had it could either be that the fittings have been over tightened or the pipes are putting too much stress on the components - this is why I prefer to do most things myself.
When I built my system to get the air out I had to run the pump at full speed (using a separate 12v power supply) and physically lift the case at different angles to persuade the air to move - it will always collect in the highest point in the section of the loop it's in, large air bubbles will not flow downwards. If you're water is dropping, but there is no leaks it must just be air finding it's way back to the reservoir.
I can't see that Overclockers will refund you in full, they might, but if not it might be worth asking them to remove the water cooling, and use an all in one for the CPU and reverting to decent air cooling on the GPU's, modern GPU's are generally very quiet, sometimes even when being pushed hard.
As Chrysalis says water cooling can be high maintenance, when I built mine I didn't want that, and I thought if all in one's could be sealed for life then why not mine. Normal flexible tubing is porous and will allow water out and air in over time. Acrylic doesn't have this problem IIRC. Also water cooling is prone to getting algae growing in it, I used pure distilled water (£17 delivered for 3ltrs) and some silver kill coils, there are no lights in the case, and athough it has side window it doesn't get much light under the desk. A year on and I've had no problems, and the water is still crystal clear. Long may it last