Oh, no no no you didn't do that! Okay, well, it's done so let's face it.. your 20 DHS( du has no 25dhs offer) is down the drain. Either, transfer the credits to someone who makes a lot of international call or use them. But one way or the other, you'll have to refill your mobile again. --
It happened to me once, glad I've many international contacts
. Cldn't find a way that could change the situation. I don't know much about phone business though, so maybe you can ask your other friends and see if they can do anything.