Last year, in "," we cited CellForCash.com as a service that buys old smartphones. Several readers have complained that they never got payment for their phones, which the company had verified to be in good working order. Customers have said that contacting Cell for Cash is difficult; the typical reply is an automated email response.

After helping Christine Dunn of Lafayette, Louisiana, get a check for her iPhone, we repeatedly asked the company's resolution team for answers regarding the uncut checks. Thus far the only one we've gotten is vague and unhelpful: "Cell for Cash handles thousands of cell phones and other devices per month and we do occasionally make an error."

Given that reply, we can't know why some customers haven't seen payment for their phones. But we can no longer recommend doing business with the company. The Better Business Bureau has received 430 complaints about Cell for Cash and its subsidiary, RMS Communications Group, in the past three years.

We will continue investigating Cell for Cash's business practices; in the meantime, programs such as Gazelle and NextWorth have proven more stable.

Have you run into a problem involving customer service, a warranty, a rebate, or the like for your tech gear? E-mail us at onyourside@pcworld.com.