nope no bank details have been exchanged. Am i obliged to contact DHL and to send the items back?

Hi just looking for some advice, a few weeks ago i asked one or two companies in china for a quote on their product "zorb balls" as i was thinking of starting up my own business, i received the quotes and in the end didn't bother buying from them. Today for some strange reason i received a delivery from DHL and when i opened the boxes they had the zorballs in them and are from a company in china that i have never even heard of.. the goods are worth around £3000. i have an invoice from dhl stating i owe them £50.08 for duty and vat. I have no idea what to do.. any advice would be great thanks