Gstr 3a

Dear Sir/Madam,

We have regularly filing our GSTR on time, and even for Dec., 2017 have filied our GSTR 3B on 06.01.2018 itself.  But, unfortunately we have received Form GSTR 3A, notice for non-filing of GSTR 3B for Dec., 2017.. Our status is showing "Filed" in GST portal.  How they are selecting the defaulters?

Further, we have claimed ITC in Nov., 2017 and adjusted the same in Dec., 2017. But the same bill was got cancelled in Feb., 2017. The supplied has not filed his return GSTR 1.  Please suggest How can we adjust that ITC and how to show the same in our return and pay the tax??

Regards