That's my point - I DID contact them to cancel my order before it was dispatched.
I called them at 11.30am, before goods were dispatched (at 3.45pm) to cancel my order. The customer support guy I spoke with said it may or may not be possible to cancel, in which case to refuse delivery. This doesn't however change the fact that I did contact them and requested cancellation before dispatch. I then looked up the DSR's and about 6pm also gave written notice as stipulated in DSR's for cancellation notice.
And yes, I have looked at the DSR's, that's why I believe I'm entitled to a delivery charge refund:
"Can a consumer cancel an order before they receive the
goods or where goods are lost in transit?
3.35 Yes. Where the DSRs give consumers rights to cancel, this right is
unconditional. If consumers cancel before they have received the
goods you must refund the total price of the goods, including any
delivery charges. Consumers who have cancelled under the DSRs
may refuse to accept delivery of the goods. Refusal in such a
situation cannot be treated as a breach of contract."
"What must my consumers do if they want to cancel?
3.26 They must tell you in writing, or in another durable medium, if they
want to cancel. This includes letter, fax or email. A phone call is not
enough unless you say in your terms and conditions that you will
accept cancellations by phone.
I was hoping to get some specific guidance on the technical points of the regulations to see if Google can somehow get around them (unlikely as that seems to me) before I pursue this matter with their legal department - which is what Google seems to be telling me I have to do to further pursue the issue.