I turned down my parents expensive trip and wanted to go on my own now they are refusing to pay for me.
What does their offer mean to you?
I was a bit angry at first but now I accept it...
You have to know that your parents are allowed to do whatever they want, including rejecting your offers. Next time you need to just accept things if they're good, because now they're all gone and you or your parents could have had a great time.
I was a bit mad. But I do follow their rules so what do they want?
In the future it is probably better to just accept the gift, it seems rude to ask them to send you on a different one. NO one is obligated to invite you along but it is nice of them.