So to update, I've had zero success with this. After taking it to Armstrong in Lower Hutt the first time I didn't hear anything back from them. Finally got around to calling them last week, was told yes they can do the updates now and I booked it in. I took in to them this morning, when I got there they'd never heard of me and claimed to know nothing about any new pak files for it. After leaving it with them for a couple of hours I got the call back saying no they can't do it. They said they'll chase it up and get back to me. To be honest I'm not expecting to get a call.
I wonder if there's any other options near Wellington.