The CBEC is responsible for the roll out of the GST. The North Block mandarins are shouting from the rooftops that everything is in place & the users should not worry but the users have enough experience of the Indian bureaucracy & they are a worried lot.
It is not that you are devising a taxation system for the first time in this county despite the fact that GST is dubbed as the biggest reform. The bitter fact is that you have run taxation systems both at the centre as well as the state & local level but then you have failed to learn & make improvement for hassle free implementation.
DGFT exists as on date & the DGFT is the policymaker & Customs simply an implementer. However, under the new GST regime, there seems that the authority of the DGFT is totally undermined as if that authority does not exist anymore. However, it appears that the DGFT in itself has brought upon them this situation.