Yes - have just received a response from them:
I am sorry for any confusion regarding the number of discs included in the Spiderman 4k Steelbook.
I can confirm that the Spiderman 4K Steelbook does include 3 discs and not 4, as advertised on store.hmv.com. As you probably have already found, your steelbook contains a 4K ultra HD, a 3D Blu Ray and a 2D Blu Ray disc; however, please be assured that all of the bonus content that was intended to feature on the 4th disc, has been included on the Blu Ray disc instead. We would like to assure you that while the format of the product varies from our listing, all of the bonus features advertised are still included.
Should you no longer require this item, we ask that you return this item to us as originally sold, with all digital content unredeemed, for a full refund.
Apologies again for any confusion caused and I do hope that this information has clarified the matter. Please feel free to contact us should you require any further assistance.
Kind regards,
Jordan.
Customer Service Advisor
store.hmv.com