Wrong Tv?

i had a 50 in" plasma panasonic tv on layaway at the Lancaster SC store since August 2012. i went into the store tonight and paid the layaway off and picked up what i thought was my tv. The tv i laid away was a display model without a box. the one i received was in a box. when i got home with the tv i had a message on my answering machine from the store saying they gave me the wrong tv and i needed to return it. on my receipt it says all sales are final no refunds and no exchanges shouldn't this mean the same thing? it wasn't my fault they gave me the wrong tv. i asked what the difference was the clerk told me about $170 difference in price. the only difference i see is the one they gave me was in a box and the one i laid away wasn't it was a display model. i feel i paid for the tv i brought it home all sales are final this tv is mine. i have the paid receipt to prove it. they said they would come pick the tv up if i call back and give them directions to my house. i told them i won't buy anything else from them. they are going out of business next month. i feel i shouldn't have to return the tv this wasn't my error.