2 debit orders within a week.They are **********

I bought a wealthy plan policy for R300 per month for 20 years.We agreed that the debit order must go off on the 28th of each month.The first debit order went off on the 28th of November 2015. And on the 5th of December second debit order instead of the 28th, I phoned them and they gave me a stupid excuse so I cancelled the policy.They said they will only refund me R180. Thats reallly unfair.