Unhappy about charges to an overdraft amount available on my account.

Unpaid item fees is ridiculous on my account...FNB allows one or atleast me to use an overdraft amount on my account every month and after using it their charges are ridiculous and they charged R1215 today, and yesterday there was a charge of R200 and something. This has never happened before and I want a refund on the R1215 charge. I won't use that feature on my account again it's ridiculous.