Email support@ugwo.ng with what happened, what you expected instead, and which invoice, client, or page it involves if relevant. We reply from that same address.
Before you write in
Check the status page first - if something's down platform-wide, it'll show there before we can reply individually.
Billing questions
Subscription, invoices for your own account, or payment issues - same address, mention it's a billing question.
How the product works
See the docs for how invoices, quotes, credit notes, and approvals fit together.