You mean you're not receiving the security/authentication text messages? Or is it trying to do this via your bank's online banking app (PTSB and maybe other banks do it that way)?
You might need to contact your bank's support and ask them what's going wrong.
If you also need to contact 48 support see the link in my signature below or email them at support@48months.zendesk.com
While you're here, check out our "Featured Topics" below.
Our Troubleshooting Guide and Knowledgebase contain help and support articles and popular questions to help you as a 48 customer.