R4100 of data in 1 month?

I upgrade my sons phone in April this year . The previous contract had a block (to control the limit) on the contract. 1 Month after the upgrade I received an account of R4100<br> How is it possible? I went to the store in Standerton, and Franciska Basson confirmed it was data. <br> I mentioned to her that the contract has got a block on and it is not possible. She said that the block was not on the new contract and the system probably was overloaded and it was not put on the contract. <br> The day I upgraded the documentation was not discussed with me I just had to sign on several places. How must I know what everything means on the documentation. <br> The adverti*****t clearly state the \my choice packages"is to not have surprises. I did not apply for a new contract I just upgrade on the existing contract. My telephone number does not change"