GSTIN OF E-COMMERCE OPERATOR

I selling products on Flipkart.
I have Tally erp-9 software
At the time of generating GSTR-1 from Tally, it do not show all b2cs entries. All entries are showing in incomplete.
It shows invalid GSTIN of e-commerce company.
As per Tally GSTN of e-commerce company should be in formet -- 24ABCDE1234H1CW. Means second last character MUST be " C "
In offline template provided by GST Dept, in sample data shown is showing same format of GSTN of e-commerce co. second last character " C ".
But while contacting Flipkart and Snapdeal, they are saying that their GSTIN is OK. second last character " Z ".
Please help me, what to do ?
Thanks.
Manoj Kedia