Complaints are piling up over courier companies' "snail"-paced delivery of packages.

It follows a record backlog of parcels from the start of level 3. NZ Post and other courier companies have begged customers to show some grace.

Four weeks' worth of purchases were frozen during level 4, meaning a surge of deliveries in level 3 that overwhelmed courier companies across New Zealand.

Since the Herald reported the case of an Auckland University student whose studies are being hampered by NZ Post's courier services that have kept her waiting for a laptop for weeks, other people have complained about slow and poor service.

Edelyn Chiew sympathised, saying she, too, was a university student who needed her laptop for online classes and was "super frustrated".

She sent her laptop to UberTec to get it repaired on May 16 and paid $20 for a one-hour delivery service from Deadline Couriers.

"It has been one week and it still hasn't arrived," she said.

The Auckland University student's mother, Trish Boniface, said the family used NZ Post to send the laptop to manufacturer Lenovo for repairs on May 5.

She said it took NZ Post seven days to get the laptop from Mairangi Bay to Mt Wellington. After taking two days to fix, NZ Post picked it up on May 15 and it had still not arrived by May 23.

"It is impossible to get in touch with NZ Post at the moment to be even able to talk with someone there who can deal with this problem," Boniface said.

NZ Post said it would look into the Bonifaces' case.

Geoff Dawson said on May 12 he bought an oxygen concentrator from BOC in Auckland for a client in Rarotonga.

It was picked up by CourierPost the same day. It was booked on a flight leaving Saturday, but did not turn up. On May 21 using Track and Trace, he found it was still in the Highbrook depot.

"This is disgraceful, you can't get through on the phone. BOC aren't having much success either," Dawson said.

Peter Lee, of Broomfish Automotive Parts, said he used CourierPost, which is owned by NZ Post, for all his deliveries. It took two weeks from ordering CourierPost tickets for them to arrive.

"I was on hold for 45 minutes for customer services, only to be transferred to another number that rang 25 minutes before I gave up.

"I had customers waiting up to three weeks for deliveries of car parts to get them back on the road," Lee said.

Dave Mason said his wife's new passport was sent by overnight courier on May 8 from Wellington to Orewa and had still not arrived.

"Tracking showed it got to East Tamaki the next day where it sat for weeks. I could have picked up her passport and had a leisurely walk in the beautiful sunshine at this time of year and it would still have been quicker than CourierPost," he said.

CourierPost said on Thursday it still had 150,000 parcels from the start of level 3 - almost four weeks ago - that haven't been delivered.

Other courier companies said parcel delivery volumes hit levels similar to Christmas but without time to plan for the on-rush.

This came on top of physical distancing, contactless pickup and delivery and other safety measures because of the Covid-19 pandemic that further slowed deliveries.

"NZ Post wishes to sincerely apologise to customers who are waiting on an overdue parcel, as we clear a record backlog caused when NZ went into alert level 3," chief executive David Walsh said.

"We expect to have the 150,000 parcel backlog of items sent at the beginning of alert level 3, moving through our network and on their way to people over the next week."

He said NZ Post received more than 3.5 million parcels in the first two weeks of alert level 3 as more shops opened up online.

This was combined with the backlog of retail shopping that had been bought during level 4 but was unable to be delivered.

Walsh said the number of parcels has been unprecedented.

However, those parcels were now starting to move through its system.

"We are doing everything we can to get your items to you. We have set up temporary processing sites, and are operating 11 sites 24/7 for the first time," he said.

"We've brought on hundreds of extra vans and people, and are working around the clock to deliver what you care about."

But Boniface said the delays were now stretching into an unreasonable length and threatened to have lasting effects on her daughter's education.

"This is impacting my daughter's university studies severely as she needs certain programs on her laptop for her papers," she said.

"If we thought that for one moment that it would have taken NZ Post this long we would have waited to get the repair done."