I was told by the Office Cantonal de La Population that if I want to leave the country for an extended period and preserve my Permit C, I have to write a letter to them and explain to them why do I want to leave. I can request anywhere from 6 months to 4 years absence.
Anyone has any experience with this process? Seems like a subjective process and there is no real guidelines available.
Any help will be very appreciated.
Ahmed