Not that complicated. Some offices it's possible to obtain extension 45 days prior to expiry, so the actual months in question are not that relevant. The immigration office is looking for 12 monthly transfers for each month prior to application. If application is made, say on the 15th of the month, a transfer may or may not have been made for that month. If a transfer has been made they will look for 11 previous transfers, if transfer has not been made they will look for 12 previous transfers.
Not quite correct. You need to show 12 x 65k monthly transfers leading up to the extension application. I've done this at least a dozen times at CW and have only needed 12 months or statements showing 12 international transfers
I switched from 12 years on non-O retirement visa/extension to DTV. Impeccable banking history. Never once used an agent to carry out dodgy transactions.