What *could* possibly happen?
Well, the delivery guys could refuse to fit my new washer-dryer because my kitchen is so old that it doesn't have an electrical appliance isolation switch, and it's against their regulations to fit an appliance in those circumstances (because they're trying to indemnify their parent company from being sued if the appliance happens to catch fire and burn your house down).
So they unpackaged the new washer-dryer, removed the old one and left me to fit it. Though at least the people I bought the machine off rang me up no more than 15 minutes after the delivery chaps left to refund me the installation charge part of the delivery fee. Which was as unexpected as it was welcome.
The new machine is happily chuntering through its installation wash (i.e. no detergent, no clothes) and the kitchen floor is still reassuringly dry. Thank goodness that's all over...