Invoice factoring is an agreement to assign your accounts receivable (A/R) to a factoring company. So the letter communicates that a third party (factoring company) is managing and collecting your A/R.
You need to consider the fees associated with switching before committing to the change. Once you've decided to leave your current factor, you will need to give notice. All factoring companies require written notice to terminate the contract. The expectation is usually 30 – 60 days prior to the renewal date.
Factoring is a financial transaction and a type of debtor finance in which a business sells its accounts receivable (i.e., invoices) to a third party (called a factor) at a discount.