Rejection of goods

Hi,

I have O. G. S. purchased goods on 24/03/2010 and 30/09/2010 with these two invoice. Now the ggods is not as per our specification so we are rejecting the same.

But seller told us we are accepting only if your are paid (CST and Excise) already paid on purchase of goods?

How can i resolved the issue without paying the (CST and excise)

please reply as early as possible.

Thanks