I used Ceridian for COBRA services after I left a previous employer. (For non-Americans, COBRA is where you get to keep your employer-provided health insurance for a limited time if you pay the full cost of it, and yes it's a hassle.) I noticed in January that I hadn't gotten a bill from them in a while, and thus began months of agony where they told me they hadn't gotten updated rates for the new year from the insurance company but were sure it would come any day now. After a while they sent a notice saying that the insurance had been cancelled. Many long phone calls to them over three or four months got me nowhere, until finally frantic calling to the HR department of my ex-employer got it sorted out in a mere two weeks or so. And yes, I should've involved my ex-employer sooner.

The upshot is that I will never willingly do business with Ceridian again.