Outages with 2degrees mobile top-services are continuing to affect customers almost two-weeks after a system's upgrade started.

2degrees mobile customers are struggling to top-up their mobile phones after a network system upgrade that started last week continues to cause issues.

The mobile network announced an internal systems upgrade on February 15 on its Facebook page. On February 25, an updated message said customers could "still top up online, in one of our stores, [and] by texting a voucher code".

Are you having problems with 2degrees? Send your tips to newstips@stuff.co.nz.

But frustrated customers couldn't top-up online and started sending screenshots of the online store being unavailable due to a system upgrade.

2degrees customer Debbie McQuillan said access to the network was suppose to be back up and running on Wednesday but was extended after outages continued to affect customers.

"It's been very tricky, as I have very tight budgets to stick to, and part of managing that is being able to log in to keep an eye on how things are tracking," she said.

She said the My2degrees service online, which tracks how much data customers have used, had been down since February 15, and only became available again on Saturday morning.

"My phone is my only way to access the internet. I have to make sure I haven't gone over my data otherwise I go onto the causal data rates and those are exorbitant."

McQuillan said one online top-up service was now working after days of being unavailable, despite 2degrees informing customers the service was up and running.

"Adding to the frustration is their slow call answer times with one person showing their phone screen with an on hold time of an hour and a half - when their phone numbers are working at all," she said.

2degrees spokesman Mat Bolland said, "We really apologise to our customers. As we've brought things back online after the upgrade, we've had challenges come into play but we believe we have things working except the app."

Bolland said calling the network to top-up isn't working because the lines are so busy, and asked customers to go online.

"I don't have a time for when the app will go back online but data, calls and texts are unaffected by the upgrade," he said.

"You can top up in other ways. We recommend people don't call and we apologise for that but the wait is so long it's better to go online."

Customer Fiona Rawdon said he was initially frustrated by the continued disruptions but customer service staff had been apologetic and others needed to practice a little patience.

"It isn't actually that difficult to buy a top up voucher, most dairies and supermarkets sell them. Then just text the top up code to 201," he said.

"I was whinging but really I'm sure they are desperate to get it all back and running so happy to cut them some slack. Patience people, patience. I can still communicate on my phone so that's the main thing."