I'm an ex pat kiwi visiting NZ for five weeks starting next month and I would like a prepaid Sim card while I'm in NZ, primarily for data although some minutes would also be useful.

Usually I'm visiting for ~4 weeks so I can just pay for one month. This time since I'm visiting longer I would ideally like to purchase a pack that will rollover any remaining data or minutes to the next month so that I can continue to use the data without having to pay for another month.
Looks like a lot of prepaid plans require a top up to rollover which would defeat the point, but it's not so clear for spark?

Can someone recommend a plan that would fit my requirements?

Thanks in advance