Mobile provider 2degrees is offering customers free calling and texting to say "sorry" for a fault causing widespread frustration.

Customers have struggled to contact 2degrees and use their services to top up, check balances and manage plans over the past few days due to a fault the company said was caused by "internal systems upgrade" earlier this week.

Until 6am tomorrow, all standard calls and texts from 2degrees mobiles to local and Australian numbers are free, while the company continues to sort out the issue.

"We've been doing everything we can to sort issues and I know how frustrating it has been for customers who haven't been able to get hold of us so they can top up or buy value packs," said 2degrees CEO Stewart Sheriff.


"By making mobile calls and texts to New Zealand and Australia free today, we're saying we're sorry for the hassle this has caused and thanks for bearing with us."

Since the completion of the 2degrees internal systems upgrade earlier this week, customers have faced long wait times when calling customer care and difficulties using the 2degrees mobile App, with congestion also impacting the website.

A frustrated customer earlier told the Herald he believed the company was ignoring affected customers.

"None of the customers were notified by email or mobile ahead of the 'upgrade'. Further to that the upgrade was due to be complete feb 22 but still not working and again no Comms whatsoever.

"This is not how a company that we pay so much of our hard earned money should act when dealing with an issue."

The 2degrees mobile and broadband network were not impacted.

Updates can be found on the 2degrees website and Facebook page.