Obviously really sorry to hear that, Aaron.
To clarify, DPD offer a host of options but for some reason aren’t offering them to you in NI. We aren’t choosing to offer you less options because you’re in NI and it’s: more expensive/more difficult to us/etc. It is DPD that is not providing you with equal options to mainland UK. That isn’t something within our control, most other courier don’t offer any of these options, we use DPD because for the vast majority they do offer them.
That leads onto a great point raised about offering multiple couriers at checkout, because sometimes you know which couriers are great in your area - as there are sometimes local differences. It’s definitely interesting, but could have consequences. See below.