in order to change your credit card details you will have to manually recharge your service and select "Enter New Credit Card details" this will automatically delete your saved details. once you have successfully recharge it will ask you once again if you would like to save the details you need to select Yes and enter a new PIN to save your details.
Then go back to Home - select recharge - auto recharge - and enter the date that you prefer.
Please remember that everytime that you enter new credit card details the auto recharge information will be deleted at the same time.
It was not mentioned that if you update your credit card in the middle of an auto recharge cycle you FORFEIT the remaining balance. That is simply THEFT and a ridiculous accounting system! Don't bother calling to query or complain as you just get the time wasting run around from an overseas call centre.
When all else fails, ring Boost's Corporate Head Office in Sydney (AEST business hours).
I have called and asked for a 'Team Leader' [TL] to deal with problems on three occasions, with good results. Non of the BS that sometimes comes from even some Telstra Supervisors, at the Boost overseas call centre. [Not always their fault, just badly trained in Boost's systems!].
Remember to NOT get put through to the O/S call centre. Tell Operator that there is a specific "finaancial/ billing system problem" that only a head Office TL can can deal with. You may get directly through to a TL, but not the specialist you need. Make sure that you get the name of 1st contact, in case you have to chase up in a couple of days. [Only had to once]. They should be able to sort it for you. [I am having to negotiatethe same crap 'change card system', for a change of bank, later this week. See how I go!!
Call 02 9299 9655 for Boost's Head Office. [This is NOT the Telstra overseas contracted system, that you have dealt with prior.] Number came from White Pages, a few yearsago.
Good Luck, Shalama.