Can Taking Desogestrel For Long Time Cause Heavy Bleeding?

I have been taking the mini pill desogretrel for about 2 years, for the first year and half everything was fine, slight bleeding every now and again but nothing abnormal. However, the last two times I have received my prescription the packaging and name has been completely different on both occasions. On the first instance I went to the doctors as I was suffering from heavy bleeding for over two weeks, acne, mood swings etc... My doctor advised me to carry on taking the pill and see if this ended. After a few weeks it did, however after my 3 month supply ran out I was given a new prescription again different name and packaging. The doctors assure me its be same pill as I was takingn a year ago but I am again bleeding very heavy for over 2 weeks now, I am currently taking Feanolla. If the pills I am receiving are the same then why is this happening every time I get my prescription. Can you advice me on what to do, I wish to stop taking the pill but I am worried this will cause more problems then I am currently having. Thankyou for your help .