How to stop raincoat inner waterproof lining coating peeling?

"Hey Suze,

If the lining is peeling it will need to be replaced. There is no easy way to do this. If you are an experienced seamstress, you can replace the panels with another layer of fabric on top. If you are unsure or need help, contact Patagonia customer service for a repair."

It may be under guarantee still. Bring it back to the original purchase place with the receipt, they may replace it for you.