I'd be more inclined to write a pro forma letter, then sue for statutory damages for technical violations under the FCRA and/or FDCPA the instant the establishe

I'd be more inclined to write a pro forma letter, then sue for statutory damages for technical violations under the FCRA and/or FDCPA the instant the established deadlines pass. It puts the burden of proving the validity of the debts on them, and if they ignore you or drag their heels, you win by default.