Prime Video debited me twice

I started a 7 day free trial with Prime Video on the 9th of March, while still on this supposed free trial I was debited on the 15th of March, I let it go because I decided I might as well watch it for the rest of the month. But then I was debited again on Monday the 18th, so I was debited twice for the service. The worst part is that you can't even reach them to complain, I have searched everywhere to complain, the numbers that are on the internet are for oversees. I have been trying since Monday to reach them unsuccessfully. I'm cancelling them after this month. I have both Netflix and Showmax, I have never dealt with this kind of nonsense with them before.