You need to contact 48 support about this.
Nobody on the community forum can do anything about it.
FWIW I have had the same issue (getting refunds of credit after leaving) with many other service providers.
I reported the issue to the relevant consumer protection authorities but they did nothing.
Hope this helps.
That's frustrating alright.
Maybe try the complaints process?
https://48.ie/legal/code-of-practice
Hope this helps.
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.