Having breakthru bleeding for 14 days, been on quartette 3 years. can i double bc pill dose to stop bleeding?

Not unusual: Break thru bleeding is very common on oral contraceptives but it does tend to diminish with time. Taking a double dose of your BCP is often suggested but it hasn't been clinically studied and may expose you to increased risk of the side effects of BCP's. A safer alternative would be to take an estrogen supplement for 7 days to reduce the bleeding. Discuss this with your physician.