Research
So lets try to figure this problem out 
https://letsencrypt.org/docs/rate-limits/
The specification is quite obvious however one needs to figure out but how do all these things tie together
A) Authz Limits are tied to an account
B) A really good attempt: Tool for clearing / invalidating pending authz
C) Some documenation https://letsencrypt.org/docs/rate-limits/
Challenges for me:
A) Where are these authz been generated
B) Who keeps the score
So in order to figure these things out. Let’s induce some fail conditions aka throw some spanners in the works (and i have to confess this is the best part of the job )
Andrei