I just bought a Samsung Galaxy Smartphone. I put a Mobily sim card in it (which my company gave me in a nokia phone, when I first arrived three weeks ago). And I went to a Zain store and paid 75SR for one month and 200 minutes of calls. However, I still can't use the phone - I can't make any calls. When I try to, a Mobily message says I have insufficient credit, but I have a subscription with Zain. I don't know what to do. Could someone please advise me? Many thanks.