You can top-up your Plum savings (i.e do a saving transfer) by typing 'save' in Messenger. Alternatively you can tap the 'Save' command in the Messenger menu.
To transfer the money into your Plum savings we will issue a Direct Debit payment from your linked bank account to Plum which usually takes 3 working days to reach us. During this time, your saving transfer will be marked as 'pending'. You can read more about the saving transfer timings here.