@Alistair24, I'm an AIrbnb superhost from Australia, I am so sorry this has happened to you but can I assure you Airbnb take host cancellations very seriously. These hosts will not only find their calendars blocked from taking other bookings for those dates of yours, they will be fined a monetary figure that is greater than that price difference you stated. They will have an automated posting put on their reviews that says they cancelled a guest reservation and this will affect them for years to come because guests do not trust hosts who have a record of cancelling guests bookings. And if they do it 4 times Airbnb will suspend their listings for a period of time and if they do it again in a one year period Airbnb will close their account!
And for you as the guest Allistair, if a host cancels Airbnb will help you find another listing and if the cancellation is within 28 days of your stay Airbnb will give you a 10% bonus towards the cost of a more expensive reservation.
There is however a way around this whole scenario!
On the top of the property search page you will find a series of filters for setting your search criteria, number of guests, price, Instant Book....and lastly 'More Filters'. In this category one will say 'Superhosts, stay with recognised hosts'! By applying that filter only properties of hosts who have not, and, do not cancel reservations will be displayed and you will be able to book with confidence your reservation will be honoured.
So sorry you have struck this Allistair and I as an Airbnb host don't like this any more than you because it becomes a slur on all of us who go out of our way to do the right thing and make our guests stay special....it makes all of us guilty simply by association!
Please don't destroy the barrel because you found a couple of rotten apples in it!
Cheers.....Rob