Maybe it's a co-incidence, but both of my orders with Scan have resulted in a delay because some trivial component which I added to the order (in this case a wi-fi dongle) was 'out of stock'.
I placed the order at about 2pm, got an email at 9pm. How on earth does 'next day delivery' map onto 'we'll delay your whole order for a week in order to fulfill a £10 component'.
Sort your stock control, or swallow the cost of multiple deliveries in cases like this.
Wondering why I should ever consider Scan again, and need to post myself a note somewhere public as a reminder.