Written Agreement not Honored by Standard bank

Again with Bad service from Standard bank.. I negotiated a lower interest rate from Standard bank for my Home loan, which was approved on condition that I open a transaction account. So i go to a branch ask what trans action accounts they have and the say the cheapest is the Pure Save and that this account can be linked to my Home lone. Great so i open the account as agreed by standard bank.. Now when i ask them to implement the reduced rate, they say i need a cheque account, My question is .. I did everything standard bank asked of me in acceptance of a written agreement, only for the Bank to change the requirements, I'm sure the banking ombudsman will find this very interesting .. I just do not understand why the public always has problems with Standard Bank.. its ridiculous, Is standard bank trying to loose customers .. I will be taking this further as a agreement was reach and agreed upon in writing.. so be prepared for some attention on this one Standard bank..