same thing happened to me 
previously their system had an issue and i couldn't make large transfer, i managed to slip through by making multiple small transfers

then they flagged my account as suspicious
I have already called in one week go and explained that the transfers were made by me, and asked them please remove the flagging
But until today they still hold my payments for 24 hours.
imagine needing urgent money and not being able to get it immediately, wtf