Gst certificate showing 2 company names

I am Proprietor of 2 companies, Company A for goods trading business and Company B for services business.

I have got single GST certiicate which mentions Legal Name as My personal name and Trade Name as Company A. There is no mention of Company B on the certificate. 

I am facing issue because vendors of Company B from whom I buy services or goods, are not ready to give GST invoice that will bear my GSTIN No. because they say Company B is not mentioned in the certificate.

How do I solve the issue? How can I get input credit for GST paid by Company B?

Thanks in advance.

- Harish