Help is here.

I am a returning tax exempt and/or a reseller customer who has already submitted the required tax exempt documentation. How do I collect a refund for the taxes I pay on subsequent orders?

Regrettably, we are no longer able to refund sales tax from previous orders. We are required to collect taxes for some of the countries that we operate in, which include the US. However, with your account updated and tax exempt, you will no longer be charged sales tax on your future orders.