A technical glitch with Vodafone text services is causing problems for customers.
The network confirmed staff are trying to fix a problem with its text platform.
Spokeswoman Michelle Baguley said there had been intermittent problems with text-based services, including text top-ups, since yesterday morning.
"It's not affecting any calling, any broadband or anything like that. It's only affecting services that have a text shortcode. It's not a network issue.''
Other top-up options were available for pre-pay customers having problems, she said.
