Tata Docomo - Official Numbers Barred for wrong reasons

I, have been using Tata Docomo connections for approximately * years at our institute for commercial calling purposes. The two numbers being ********** and **********.
We have been paying all the bills regularly, the plan being ***/- unlimited calling local/STD.
This month the bill that was generated for both the numbers was ****/- and ****/- despite of us recently paying the bill and the number was barred without any intimation. Now when we call the customer care they say that the bill is not yet generated and on being asked that how then you have barred the number, they say you’ve crossed the credit limit. The on asking why the bill is so huge they say you must have made an international call, we said is the isd calling opened on the number, they say No it is not.. The how is it possible to make an international call?????We have even paid the amount of ****/- still the calling services of the number ********** has not yet been resumed because of which we are suffering a huge loss on the business front.