We have progressed some way with this
The issue had two strands to it; the first relates to when your basket has a mix of coffee and non coffee items, the second is the calculation of the remote area surcharge that DHL levies on certain addresses
The first issue we are awaiting a response from a supplier on. We tested it prior to launch and it worked. In the live environment it no longer works. The error is that when you have a mix of coffee and non coffee items in your basket the shipping rates for each type of goods are being added together, when it should be adding the weights of both types of goods together, then looking up the shipping rate. This should be fairly obvious as in most cases the shipping charge will be roughly double what it should be
The second issue we have resolved. It relates to DHL charging a GBP16 remote area surcharge. The way we had some European countries grouped together for efficiency resulted in false positive matches and the surcharge being applied to orders that were not in remote areas. When coupled with the first issue it could produce a shipping charge that was approximately four times what it should have been
Previously we simply did not have the ability to recharge this surcharge so were charging less for shipping some orders than what it was costing us to ship them. While this is able to be absorbed on orders of a high value it has been punitive on low value orders within the UK so we had to introduct a system that allowed us to pass on this surcharge
We will resolve the first issue within the next 12-24 hours