IPD chart, page-313

I don't think how you make the payment matters that much in terms of returning excess funds.

If a company wants to pay money to a share holder (and as a participant in this SPP, you are already a shareholder), then they will likely approach their share registry to make the payments as they are the ones with all the information about the company's investors. So your best bet for EFT payment of funds back you is to make sure the share registry has up-to-date bank account details. (I imagine it would be a similar process to how companies pay dividends.)