Double charge for a domain I can't access and you can't help me with!

Hi there,

I have Internet and a domain with Afrihost. Unfortunately, I forgot my domain details and after numerous attempts, I decided it was easier to cancel the domain. I finally did so yesterday, but today I have discovered Afrihost charged me R116 on my credit card and R116 as a debit order. I never gave permission for the R116 debit order and why am I being charged twice?