Selling one house to 2 people

Remax Midlands is carrying on with a sale of a property even after we have alerted them that we had signed an offer to purchase and the owner signed it a month ago , We signed the offer to purchase with the owner of the house and the process had already started, The owner sold the house again with the Remax Midlands agent to another person and they are carrying on with a Sale, Approached the agent to to let him know about the process that we had already started the paperwork with lawyers, bank approval for the house, He denied the sale process .Yet on the Remax social pages there’s a picture of the house marked sold with the person he sold it to and the remarks from the agent underneath the photo . A detailed email was sent to him and they are keeping quiet and carrying on with the process even after being notified of the matter .I guess the agent is more concerned about getting commission from the sale it doesn’t matter at who’s expense.