[otrs] Add custom fields in Customer information

Hi there, I'm interested in adding more fields in Customer details. It can be possible with OTRS? I think that Dynamic Fields are available only in Tickets or Articles. I try to keep helpdesk offers support if a customer didn't pay his previous bill, so a *visible* message (such pop-up, custom HTML) would be great. Disabling customers or add text comments into customer's profile are insufficient for us beacause in first case the agent can't find the customer when opens a phone ticket; in the second one, if customer creates a ticket via mail it can be difficult to notice these kind of administrative messages. Do you have any ideas? Many thanks! -- Adrià García-Alzórriz