How to work with a hostile customer/distributor/wholesaler

I just started a sales position with a manufacturer who for the past 5 years has sold exclusively to one distributor/wholesaler in a US state. This is the norm my industry. Unfortunately my company hasnt had much contact with the dist in 2 years (thats why I was hired, to support the brands with them.) So the dist has been hostile to me - they wont return calls or emails - and they are sitting on +200k worth of product.

I want to work with the dist sales force but I get the cold shoulder from upper management. Meanwhile I'm not trying to sell the dist new product, I just want to help sell through the old product.

Any ideas?
Thanks.