Two pizza delivery employees at Papa John's learned you never know when you'll accidentally dial a customer--and leave a racist voicemail that gets you fired.

And Papa John's learned something, too: Responding to an ugly incident with a Facebook apology will only get you so far. 

Two drivers for a Papa John's store in Sanford, Fla. delivered a pizza to an African-American home. After dropping off the order and driving away, one of them accidentally dialed the customer's phone. The two left a lengthy voicemail filled with racial slurs set to music from Gioachino Rossini's opera, The Barber of Seville.

They claimed the customer hadn't tipped, although his track record suggested otherwise. But that wasn't the worst of it: The customer was so angry he posted the charge slip with the message online. 

"The only thing I've been authorized to say is that as soon as I found out about it, we looked into it right away," Keith Cooper, manager of the Sanford Papa John's store, told Inc.. "We moved very quickly to separate those team members from their employment. We don't tolerate that kind of behavior."

Papa John's tried to combat the incident with a lengthy apology on Facebook from CEO John Schnatter. However, reader reactions were mixed, suggesting it will take significantly more to satisfy the public.

"Friends, I am extremely concerned to learn about the reprehensible language used by two former employees in one of our restaurants. Their thinking and actions defy both my personal and the company's values, and everything for which this company stands. The employees responsible for this absolutely unacceptable behavior were immediately terminated.

"My heartfelt apology goes out to the customer involved, his family, and our community at large. I am very sorry that anyone would be exposed to these hurtful and painful words by any person involved in any way with our company.

"Thank you for your important comments. I have personally reached out to our customer to share my own thoughts and offer my deepest apology."

Although there were some supportive comments, the post got many negative responses. Here's one from Facebook user Susan P. Zealley:

"Now you call us 'friends' it wasn't long ago that you were going to pass on any increase over healthcare to us 'friends' so that your shareholders wouldn't have to suffer ... 11 cents per pizza as I recall ... Your company continues to be a joke." 

And here's another from Nathan Davis:

"Keep your apology and your nasty pizza! These employees got caught because they are idiots, but they had to feel some comfort in their thinking and language that your corporate culture tolerates, if not endorses." 

The company is clearly not out of hot water, and repairing its reputation could take considerably more effort.

Experts in corporate apologies generally say words alone are usually insufficient. The company must take strong action to ensure the situation does not happen again.