Is one good turn awoof? Does it deserve another? Someone helped you but you feel it's there right to help, not choice. To me one good turn deserves another.
Anyone who didn't return a favour don't deserve to be helped, Whoever receives a favour should have a mind to repay back. It doesn't necessarily mean the person must pay back with same way giving but showing kindness and being appreciative of help render to you is also a way of returning favour.
Don't forget many favour done to you because of just single mistake the person did. One good deserve another.
We have the saying "it is better to give than to receive". When we give do not expect in return. But it is in our nature to give back on the kindness showed upon us. We repay whatever blessings received even if we don't ask it, because it is not their duty to help us, to give us in need, it is our duty to care for ourselves. So, we must be thankful to them and help them when they are in need.