Didnt clealy show there was a charge for updating

I got a letter requesting me to check and update info for a web register -South Africa-which I did and signed the changes in August 2014. In October 2014 I got a letter saying I owe R9372 for publication of the register. Only then did it see at the bottom - very small on the page where I was asked to send changes did it say there was a charge. I have written to then to say I cannot pay this amount as I don't pay for advertising and if I did it would be with a South African company and not an overseas one.<br> if you need me to send supporting documents please advise.<br> They are now sending me reminders with extra charges being levied.<br> Please give me some advise.