NOTE: Bambora is sending emails to all merchants who are not passing a CVD (CVV) value with their transactions, because starting October 1, 2018 all transactions missing a CVD will fail.

TWO THINGS TO CHECK:
1. Admin->Modules->Payment->Bambora/Beanstream->Edit ... is your "Require CVD Number?" set to True?
(NOTE: This setting may not exist if you've upgraded to the Bambora v1.60 module, since the setting must always be True.)

2. Are you using v1.60 of the Bambora/Beanstream payment module? If not, Upgrade here.

You need Bambora module v1.50 or newer for 2 reasons:
a) in August 2018 Bambora required switching to use API transactions, and this support was added in v1.50.
b) v1.50 of the module forces the CVD setting to True.
and v1.60 of the module removed the CVD setting since it assumes it to be always True per Bambora's new requirements.