Help with Luna’s surgery

Hi my name is Garry and this is mine and my families loving pet Luna. She is an 8month old german shepherd. We found out a month ago that she has hip displacement. Unfortunately due to the condition being a common defect of the breed the insurance have said they will not cover it and any insurance we go to now will not cover any injuries found out before the cover started. We have had an estimate from her vets and its £4498.58 but i am asking for up to £5000 just in case they are any hidden charges or difficulties during her surgery. I thank you all in advance and just wish to see our loving Luna not be in pain anymore.