Installation Problem

Hi all,

Please help me very urgent. In my office 3 nos of internet ISP(1. Airtel, 2. TATA, 3. TATA). In my look how to configure in this 3 nos of internet grouping i.e. Group A=10 PC(Airtel connection), Group B=10 PC(TATA connection) and Group C=20 PC(TATA connection) and any internet problem so autometically change other two network. Please help me this is urgent.

Thanks
naba