No Free Minutes

I always receive 60 min monthly to call other networks but this month by the 7th of August I couldn't make any call. I called the call centre for further assistance but i got none as I asked for a proof showing the dialed numbers for 60 min but that was not available but i was told i have to understand my minutes are finished.

On previous months ill be having 15 - 20 unused minutes which i understand they cant be carried over to the following month but this month is not even yet mid month but all minutes finished, i find this so hard to believe.