EyeGlass World Bait and Switch followed by extortion Pensacola Florida

Eyeglass world offered by one get one free.  I spent an hour waiting on the employee to verify my insurance benefits.  Got a price.  Paid for the glasses in full.  Then, almost 3 months later I get a letter in the mail claiming to be a second notice that I owe an additional $40.  The insurance paid exactly what they told the employee they would pay, but Eyeglass World recalculated what was owed and decided it was $40 short. 

I talked to their representative and was unable to get a clear answer as to why.  They oscillated from saying I was ineligible for the Buy one get one offer to saying that the insurance didn't pay what they expeected, even though the insurance company paid exactly what they told the store employee they would pay for at the time of purchase.

Finally I was told I either pay the $40 or they would turn it over to a creditor and screw up my credit. So I paid and promised to let everyone and his brother know they couldn't be trusted.  Thus, here I am.