Vending Machine Weirdness

Froz: Identifies desired can of lemonade
Avanti 134908: Indicates price at 60 cents
Froz: Inserts 2 Quarters and 2 Nickles into slot, selects lemonade
Avanti 134908: Blinks “Use exact change” light
Froz: ?
Avanti 134908: Still blinking
Froz: Pulls “Coin Return” lever
Avanti 134908: Distributes 4 Quarters, 2 dimes
Froz: Considers quitting day job, moving to Reno
Avanti 134908: Stands obliviously ready to serve
Froz: Tries his luck again
Avanti 134908: “Use exact change”
Froz: $$$! Pulls lever…
Avanti 134908: Returns 2 Quarters 1 Dime
Froz: Sighs, shuffles down hallway
DVCB 600 CC: Indicates ice tea for 65 cents
Froz: Inserts 2 Quarters, 1 Dime, and 1 Nickel, selects tea
DVCB 600 CC: Makes faint mechanical noise
Froz: Pulls coin return lever
DVCB 600 CC: “Sucker”
Froz: Still thirsty, walks back to office kitchen and pours a cup of tap water.