Do not try to treat the bag yourself, because if not done properly, Hermes will then not fix it anymore as they will say you have tried to have it fixed somewhere else which caused the problem so they will not handle the bag anymore.
Bring the bag to any H shop and ask them to look at it. If it needs to go to spa then the SA will give you a piece of paper with details written down. They will take your bag, show it to their craftsman (who is in HK), and then call you back to tell you whether it can be fixed and what the cost will be. I find their cost to be quite reasonable. You can then decide if the charge is fine and whether you want them to go ahead and fix it for you. It will take about one month.