OP, I am with AIB, via my online banking I set up standing order from my current account to my mortgage account. Every month AIB then send me a letter saying they received an out of course payment and which has been applied to my balance. Then my normal monthly amount reduces by a small amount. Every few months I increase the S/O amount to take account of the lower monthly mortgage payment.
The great thing is I am in full control so can stop, reduce or increase whenever I want and don't have to write letters etc, all done via online banking.