Most Breeders do sell kittens with nonrefundable deposits, so that part of things to me, is standard and customary. I, myself have purchased in this manner countless times over my 11-year involvement with the Breed. When someone elects to purchase from me, I believe it is because they have shopped around and have decided that they want a kitten from MY lines as opposed to those from another cattery. Our contract DOES clearly spell out the fact that all deposits are NONREFUNDABLE, however...so this is something that is disclosed up front and our clients have the option to move forward with us (or not) based on their agreement to the terms of our purchase agreement.
In the case you have described, a few things bother me. First, is the fact that you have no contract spelling out the terms of your agreement, which to my mind is unprofessional at minimum. Secondly, it is always dicey to purchase a kitten from a litter that has yet to be born. Presumably, you made the decision to speak for a kitten from a specific pairing based on your strong favor for other babies born of the same pairing. If this is not what motivated you, I have difficulty understanding why you would offer deposit on a kitten sight unseen. There ARE many folks who DO place deposits on kittens from a specific pairing...so this process, in and of itself, is not unethical, provided all parties to the transaction are clear on the terms of the arrangement, which in your situation does not appear to be the case and is therefore problematic.
In absence of a purchase agreement/sales contract, is there information disclosed on the Breeders website outlining the terms of sale or stating that deposits are nonrefundable?
I am not familiar with laws in the UK, so cannot assist with specific information regarding challenging the terms of your purchase, but if the information was disclosed and you moved forward with your purchase, you are likely bound to the agreement and the promise to await a pending birth.
If it makes you feel any better, I waited nearly TWO YEARS for the birth of my first two Savannah house pets some 10-years ago. Litters were reabsorbed, kittens were stillborn and others were compromised in some fashion....until finally both of my boys were born, lived and eventually came home to me.
Based on what you have shared, I think you are going to have to be patient. Breeding is not an exact science and things happen that are not within a Breeder's control. It is unfortunate that personal circumstances have changed in your world, but it is not a realistic expectation to assume that changing your mind for whatever reason entitles you to change the terms of your purchase or a refund in full.
All best,