What price were you charged on dispatch? I have had many refunds on preorders some as insignificant as a penny. They promise the lowest price up to the close on business on day of release. e.g. using GTA release dates; if they shipped on Monday and charged you £50 on dispatch and on Tuesday (day of release) the advertised price was £35 they will refund your payment method with £15.
I was charged the same. I received an email telling me how much I had saved since the date of my order (£33.47 as I ordered at £119.99), but not one suggesting a refund. Fingers crossed I do get one too!