Day time window on prepaid mobile phone recharges

Local prepaid mobile phone credits all come with different day time windows, forcing the consumer to credit their prepaid account once the day time window has expired.
The consumer is purchasing a service from a mobile phone company, thus allowing her/him to spend x minutes on calls, data or SMS/MMS. This prepaid credit should never expire.
When the consumer terminates his agreement with the provider, the remaining credit should be refunded to the client. This is common practice in other countries in Europe and has been for example enforced by court decision in Germany.
Reference:
Oberlandesgericht Muenchen, Az.: 29 U 2294/06, February 2006
http://www.bvdw.org/index.php?id=491