Update: Minersource contacted me and said that I need to pay another $30 for shipping or get a refund based on a reduced amount of BTC because the exchange rate has changed. They said they don't even have the PSUs in stock despite listing them on their website as "in stock" over a month ago. I filed a complaint with the FTC and I am waiting for a response from Minersource. 

Anyone know which payment processing company they use, so I can contact them next?