Rarely will you find an invoice factoring company that will make advances on consumer invoices. That is, debts owed by individuals rather than businesses. Factoring is primarily a B2B (business to business) financing mechanism. This is largely due to the way the legal system handles a consumer transaction as opposed to a business transaction. The factoring company is not set up to work with consumer issues. Accounts receivable financing is based on the overall creditworthiness of your customer which can be found through business credit reporting agencies.
There are however finance companies that will handle consumer invoicing, but you would need a minimum of $500,000 or $1 million to get their attention. Most players in that arena work on multi-million dollar aggregate amounts.