Don't volunteer-they will scam you
 

Recently there was a call for volunteers since the flight was over booked. I was told I would be placed on an alternative flight which would get me to my destination 2 hour later. This was fine with me since it still gave me plenty of time to pick up the package I was to pick up in L.A. before flying to new Zealand that evening.

I recieved a $400 voucher but as soon as the flight left I was told they had made a mistake and there was no room on the flight they told me I would be transfered to. They eventually put me on a flight but it was much later and I missed my appointment. I could accept it if they put me on a flight and it was held up but in this case they simply did not do what they had agreed to do. I was several hours late to LA and it cost me hundreds of dollars to sort the mess out. Customer service does not want to know about it. They say I was compensated. I feel the compensation was for changing to the flight they told me I would be put on, not for agreeing to be lied to.

I think they are in breach of contract. They modified the contract, agreed a price with you for the modification, they reneged on the deal. Outrageous.

Exactly, does anyone have any advise on what I can do? I am amazed that the airline accepts no responsibility.

You could try small claims, but you would need very clear evidence that

a) You were mislead
b) Proof of what you were promised
c) Proof of your losses

I think it probably just best to chalk it up to experience and don't fly with them again.