Have you tried the new Liposomal Vitamin C regime?
Please search Youtube for 'Liposomal Vitamin C'.
This will show you how to make it at home at a fraction of the cost.
Please note there are 2 types of Vitamin C, one is acidic and one is alkaline, you need to choose which is best for you. I believe, cancer patients use the alkaline version as cancer cells die in high alkaline environments.
I wish you good luck.