Zong Pakistan review: balance loss

I lost my sim and then i purchase new sim card of the same number ([protected]) from the Zong customer service Jinnah Road Quetta. i recharge the number with Rs. 100. when i check, there were no balance in my phone and i take loan it were also lost in few seconds. i not use the balance then why it lost in few seconds.
I request to the company to properly investigate why balance lost in few minutes without use. please return my balance i didnot use it. the main thing is to know how it happens.