Airtel Prepaid
No benefit after recharge of special tarrif

Sir/ madam,

I am ashish Mishra. i recharged with a special tariff voucher of Airtel for the benefit in the night calling. it worked for few days and then suddenly is not working. on asking he customer care executive, i am getting cold responses and excuses such as technical problem. They assure me to solve the problem but it is not being solved. now what should i do? please help...