How frustrating Kelly. I feel for you.
My understanding is technically speaking, a fondant covered cake can keep if stored in fridge for 7-10 days.
I agree with Elli, advise client the cake may dry out if kept that long in fridge and may not match the quality of enjoyment you intended, but should survive and be fine to eat. Advise her also to keep cake in box and place inside it a small bowl of bicarbonate soda. this will grab the humidity in the air of the fridge and support the fondant and decoration whilst kept in the fridge.
The cake could freeze but upon defrosting is likely to sweat to a degree that any decoration may be ruined so best to keep in fridge
Love, Power & Kake xxxx
