what do you do when you have an apple device under warrenty and they do not want to fix it

If Apple determines that the issue is a result of accidental damage or misuse, there is nothing you can do as the warranty does not cover such situations. You can try arguing with Apple about that decision if you wish to.

Apple will always replace devices where the consumer legislation, applicable to the region in which you purchased you device, requires them to do so. Otherwise, your device will be repaired.

For some devices, such as iPad, Apple do not offer a repair service - but will instead offer an “exchange” for a refurbished (or sometimes new) device of the same model and specification. The exchange process substantially shortens the time that you are without your device - as for devices that are still “in support”, the exchange will be immediate. If done in-store, you will leave with the replacement in your hand.