Your situation is exactly the purpose behind the DV process.... requiring a debt collector to cease collection on an asserted debt until they have at least determined and verified back to the consumer that a reasonable investigation on their part confirms that the contacted consumer is in fact the party who owes the debt.

Sending a DV is more comprehensive than sending a simple cease communication letter, as in addition to barring communications with you, it also bars any form of collection on their part, including credit reporting, until such time as they have obtained and provided verification of the debt.