1035 inherited exchange

I inherited an annuity when my mother died.  I moved it into another annuity, with a different company,  via a 1035 Inherited Exchange.   I understood this to be a non-taxable event.  I recieved a 1099R with a taxable amount.  The box 7 distribution code on the 1099R is 4D.  Shouldn't it be distribution code 6?  The issuing company will not send me a corrected 1099R.  How do I correct this?

Thanks for any advice!