How to reply to a complaint letter in business english

from: a us wine producer
to: the firm responsible for shipping its wine

I am not happy about the last 3 times you sent our wine to Europe

a)the people who bought the wine were angry that they got it two weeks after they were supposed to. Seems like you'd forgotten to pay the custom people

b)when it got there, the wine was not as good as the bottles we'd sent them before to try. they were perfectly OK when we sent them

c) you agreed to move the wine all they way from where we make it to the people buying it. that included looking after it properly on the way

d)in the end we had to charge the people who bought the wine only halt as much as wanted to. we want that money back from you- through the courts if necessary

And I want to hear from you IMMEDIATELY

can you please help me with this? this is my homework and I cant do it right...