Plusnet cancellation prior to installtion

[#1]

I signed up for Plusnet on October 26, paying in advance for set-up, modem etc and had an engineer installation date of 9/11/12.
Today I have received texts and e-mails to say that the visit has been revised for 13/12/12, which is too far in the distance for me to be without services.
I understand that I am within the 7 day cooling off period under the distance selling regulations to cancel without charge and have my advance payment returned.
Looking through their Terms and Conditions it states:
13. Cancelling before the service is activated, or under Distance Selling regulations
Any non-business service from Plusnet, under Distance Selling regulations, can be cancelled, without penalty, within 7 working days.
For a broadband activation, the 7 day period starts on the day the line is installed, but if the service is used at any time the right to cancel is lost.
For supplied equipment, the 7 day period starts from the day after the equipment is received. We will not pay the postage costs for the return of the equipment in these circumstances.
Any third-party costs associated with activation of the line will still be payable (such as partial or full activation fee). These costs are applied to us by our supplier.
If the request to cancel the line is received within 48 hours of the date it is due to be installed, the full cost of the line will be payable.
A sliding scale is used to determine how much is payable if the cancellation request is received more than 48 hours before the line is due to be installed.
The line 'Any third-party costs associated with activation of the line will still be payable (such as partial or full activation fee).' concerns me as it seems to be saying that they have an option to make some kind of charge.
The statement 'A sliding scale is used to determine how much is payable if the cancellation request is received more than 48 hours before the line is due to be installed.' does not then list this sliding scale on the page for me to view to clarify.
So as nothing has been done in terms of supplying equipment or a service, will I be entitled to a full refund for all advanced payments that I have made?

[#2]

Under distance selling regulations, this indeed does entitle you to a full refund for services that are yet to be supplied and upto 7 days from services starting (or installed, depending how the circumstances apply to your activation).
With the supply of goods, it is a relatively simple process as the item is either supplied or it isn't. With services though, this is a little more complex.
Although you have been supplied with a physical installation date in the future, other required work does take place in the background. Some of these include setting up network paths for your connection, to the work needed to allocate your line to a specific port the engineer will use. Much of this takes place in a few days prior to the physical install, others sooner.
It is these works were charges may apply and although we quote a sliding scale, the fees are both fixed in their value but also the points at which they apply. One example is that cancellation of an order on DSL within the 24 hours prior to completion incurs full costs, including cease fees.
In your own case, I would not expect any fees to apply due to the amount of time before activation you have made this decision. The only exception could be postage and packaging if the unit has already been sent, but we would cover the cost of the actual return if we had sent it out.