Thank you for the help, much appreciated.

The other great feature on iShipping is that I can select "drop off". This isn't an option on BAC and was always a hassle booking returns where the customer didn't want a courier pick up. I can also ship a replacement product and include a return label with the drop off option. This is much better, I'm so happy.

Okay, that's great news for my business then. I got excited, and then disappointed when I noticed the height measurement. Increasing that to X cm puts the price at $10.67 even if the dimensions are identical. Makes sense for what you mentioned earlier, how it's more for a box that doesn't fit a preset bag size. ishipping is just a service, parcels go through NZ Post just the same as they would if going through BAC I presume?  Now I can start providing free shipping over $100! just like other stores, this will surely help for Christmas sales. Thank you very much for your time :)

Thank you so much for the help Gary, and Callum for your answer too. The only thing about the rates is that the height for most options are below every single item I place in the bags. Does it matter if they're more? BAC doesn't have any height restrictions.  

Hi Gary, Thanks for that, I appreciate it. The postage options for the preset sizes, are they for if you already have purchased the NZ Post Bags or iShipping Bags? Do you need to use the "custom package" size if you have all your own plain courier bags? A custom size with the same preset DLE size is 2x the price. I guess I should just contact CS.