Well, I did indeed write to WHSmith, and here is the answer I got:
Thank you for your recent email.
I am sorry to learn of the poor quality of this product.
I will look in to this matter and report it to the relevant department so that it can be reviewed.
As this would've been downloaded from a third party site you would need to contact them directly to arrange it to be re-downloaded.
Kind Regards
Customer Service Coordinator
Happy to learn they will look into it, no so happy a redownload is not guaranteed
should the problem be corrected. Oh well...