Sounds like a typical "Drop-Shipping" setup.
The essence of a drop-shipping trader is simply that they take orders and pass them direct to the manufacturer (or distributor) to ship,anonymously....taking a cut along the way. customer pays the D-S trader who then pays the supplier.
Works fine IF the partners play properly. Unfortunately , the trading-agreements don't seem to be good with this company and customers are disenchanted.
WRT the Sennheiser case, It's possible that Proviation would hope to source from a recognised stockist at a discount not available to the retail customer,- depending on the discount, there might be room for a small price-cut to the customer.
Many makers / distributors shed crocodile tears over these practices....they can say that their authorised agents do not undercut to compete with each other,-whilst selling another unit "through the back door"