SABC ****s in operation

TV Licence was due in March of R265. I paid R262.50 on 3rd June (late and R2.50 short in error) I was charged a 10% penalty fee per month over 3 months of R26.50 = R79.50. Over the next 3 months SABC has continued charging the FULL penalty on the R2.50 shortfall of R26.50 and say I must now pay R171? What kind of accounting ****gery is this?