You need to pass all this onto the agents. As their is no specific category for your problem use this link http://giff.ly/simincrease From the drop down list tap 30 Explain what the problem is in full in the further information box at the bottom Agents will reply within 24 hours
It's possible agents can refund the top up. Good luck
If you topped up the incorrect account you can contact a giffgaff agent they might be able to provide a refund, but it will be at their discretion. To contact an agent follow the link below https://giffgaff.com/support/ask/incorrect_balance , please note agents can take up to 24 hrs to reply to any queries.