Form to use to pay existing annuities into livong annuity unfound !!!!!

I bought a living annuity from Old Mutual. Then I got a payment and I asked for a payslip. That was apparently too much to ask. I then wanted to pay my Disvovery annuities into the living annuity and asked for a form that Discovery can use that has the policy number into which I must pay. So far no luck !!!! How can such a simple request take so much running up and dowm ????