Charged a pet fee anyway?
Being billed after approval is the commonest complaint in this whole subject, and it is nearly always an administrative oversight rather than a refusal. A short written request naming the approval date recovers most of it.
- Ask from the approval date forward
- Attach the approval and the ledger, nothing more
- Expect a credit within one billing cycle

An approved accommodation should end animal-related charges for the household, not the tenancy's ordinary obligations.