NSDL — Pan card correction status

Address:

600073

Acknowledgment number : [protected]

I have applied for pan card correction with the above stated acknowledgment number on 4th may 2017. The documents were sent through post and was delivered on 9th may. The status changed to "we have received the documents with reference to your application for 'new pan card or/and changes or correction in pan data'. Your application is under process with nsdl" 2 days after i made an inquiry call on 15th may.

From that day onward's my status remains the same.
There are no information on the duration to process these changes.
Unable to contact customer support as it never stops saying "all lines are busy".
When tried to raise a complaint through the nsdl site, there is no response as to know whether the complaint is registered or not.

Please update the status as what is happening at the background.
Does it really take a month duration for a simple document verification?