3. A certain user could mistakenly send high amount in the transaction without checking it and will be requested for a refund. The other party could deny and there us nothing you could do because it was your fault and no one can help you.
What benefit is there to bitcoin if you are suggesting we have another party to revert transactions that one of the participants is not happy with? Or if one of the parties involved in a deal has the chance to refund the bitcoins back to his address on the grounds that he made a mistake. The possibilities for abuse and engaging in fraudulent activities in such a system would be numerous. Don't send any transactions without making sure all the fields are filled out correctly. Pay attention to the receiving addresses and amounts. After you have checked, check again to make sure. Be responsible and think before you act. You can either trust yourself or place the trust in banks.