how to avoid romanian card deactivation (Bucharest)

Hi,

My Husband was working in Bucharest some time ago and will have to go back in the foreseeable future! He bought himself a prepaid card and he just got a message from his provider, stating that this number will be deactivated, if he does no top up the card.
Does anybody know of a service that allows you to top up a Romanian Cosmote card from another country? Can you do it over the internet by any chance?

Your help would be much appreciated, since my husband doesn't want to loose that number!

Kind regards,

Lizzy