All the plans in this category works by “DS“(Data Share). By implication, you will continue to use your plan till you reach your data cap. You will be automatically disconnected once your data cap is reached.
No code to check balance but there is always 24/7 way to know your Data usage from which you would know your Data balance.
On any SmartPhone, go to =>>Settings =>>Data Usage =>>Network.
From there you will always see your usage.
Illustration: if your current usage is 1.5GB and you procure data plan of 6GB then your total usage at end of consuming the 6GB will be 7.5GB