INCREASE OF 28,7%

Hi there, I've had business insurance since August 2013 with Auto & General. I've only just noticed that my premium increased by 28.7% which i think is ludicrous. They claim they emailed confirmation regarding this to us on the 1st July 2015, which was never received. How many companies actually gets an increase without even noticing. My premium used to be R1951 and has gone up to R 2512, which is an increase of R561 per month. Now that i've cancelled it, they wanna reduce my premium to R2018. Why increase it by so much in the first place. Will NEVER EVER deal with them again, even if they had to offer me a premium of R100.