There dosn't seem to be any PDSA hospitals in Buckinghamshire, but £3,500 is a lot of money to save if you are willing to travel.
You should contact the PDSA and ask where is the nearest PDSA hospital to you and find out if you are able to use them
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I also think you should discuss this with your breeder. Did you sign a contract?
She really should refund you some money to go towards vet fees IMO.