I've told the shop do not send me a replacement once this is all sorted out (if it's during my lifetime) , I'll come and pick it up and they can refund the postage.
My experience of City Link and all other couriers has been lots of hassle and eventually you get your item, if you're lucky.
So my new rule is... if it's going to be delivered by anyone other than Royal Mail, forget it. Royal Mail may not be perfect but they are the most reliable in my experience, and it's only a short walk to the sorting office to pick-up parcels. So I'll put up with Royal Mail's daft opening hours over the 2 hour round trip to an industrial estate the other side of Heathrow.