I appreciate that there are a couple of Ideas around this, but they have been merged into a more complicated 'flexible email templates' idea. ( i.e. https://ideas.isams.com/ideas/MIS-I-479)
Given the number of support queries these emails generate, as a 'quick win' please can you just update the copy of the existing (non-templated) locked account email to make clear
that the account has been locked, not disabled
if possible how long it has been locked for (nice to have, not worth delaying the other static copy updates for)
that it will be disabled after further unsuccessful login attempts
to use the Forgotten your details? option if unsure of your password as this will not be possible once the account has been disabled.