Thank you for your post and welcome to the Bose Community.
I'm sorry to hear that the Power/Bluetooth switch on your QC35's is broken.
Is there physical damage to it?
It is not possible to just buy a replacement switch and we do not repair headphones due to hygiene risks, however, I would recommend contacting your local customer service team who will be more than happy to advise you of the next steps. Global Contact Us > Select your country > Scroll to the bottom of the page > Click 'Contact Us'.
Let me know if you have any further questions.
Charlotte G - Community Support
Thanks for getting back in touch.
It is not possible to user-replace the power switch for the QC35. Replacement components such as this are not sold by Bose. Please reach out to local support via the provided link above to discuss service options.
i did reach out. My local team still cannot provide a replacment swtich. Surely this would be much cheaper than spending over £200 for another pair of theadphones, that only last 2.5 years!
What can you do?