India Post — Non deliverance of parcel though showing on site as delivered

I had ordered my bank cheque book in May. My bank dispatched it on 8th of May (JB[protected]IN) but it hasn't be delivered yet.When checked on tracking site it was showing it was still in the post office. I wrote a mail to India post regarding this but never got a reply. Today when I checked the tracking details they have updated that it was delivered on 11th May. Which is not correct as no one delivered it to me or called me regarding this.

I am quite frustrated that such important articles are treated in such way by India Post. Pl do the needful and let me know about the real whereabouts of my parcel.