Inability to change payment method from March to O

In March 2015 I requested change of payment method from stop order to debit order. This task appears to have been very difficult for a Mr Sphiwe Vilakazi at the Long market road branch of Old Mutual. Until now I am being sent letters of demand to pay my premiums yet I have filled in the relevant forms. To make it worse when I told Mr Vilakazi about my frustration he didn't offer an apology as it was his bungling in the first place. He told me proudly that other companies also have their issues. Even if they do they probably apologise when they have erred and they would have by now fixed a simple task like this one.