I think the writer has been issued with a breach notice.
The breach notice must include dates and times of the offence.
If you can prove you were not there when the offence occurred, ignore the notice (till the OC takes you to the tribunal for a follow up offence and you prove the notice was issued incorrectly) or go to the committee/ strata manager and prove that you weren’t there when the offence occurred and ask them to rescind the notice.