vonage is absolutely unreliable

Signed up for Vonage returned first and second equipment that did not work within the 60 day trial period, they refused to give me a refund instead sent me to collections with a $142 bill, they claimed they never got both equipments almost a year later eventhough i have post office receipts that shows i sent them back priority mail to their warehouse. Spoke to over a dozen reps/managers to no avail. Instead of a refund i have a collections bill?