Hi @Jon01,
I moved your topic into this existing but old one. You might deduce plans rolling over credit might be the exception not the rule.
Seems unfair when they charge per call, as you wrote. You might investigate the companies offering annual planes like the Aldimobile Value Pack, $99 p.a. for unlimited calls and text and 15GB data; unused data rolls over with renewals. The catch is the first time you can only buy it when it is offered in store, but from then on you can autorenew or renew on the aldimobile website. A few other telcos have similarly attractive plans for low use customers.
This other topic might be helpful?
