If you touch your Oyster and contactless payment cards on a yellow card reader at the same time (for example in a purse or wallet) to make a journey:
If this has happened to you, you might be able to get a refund. You can apply for a refund by contacting Customer Services on 0343 222 1234 (TfL call charges). You'll need to provide your Oyster or Oyster photocard number and/or contactless payment card number.
Make sure you only touch the card you want to pay with on a yellow card reader to avoid card clash.