In May 2019 a group of eight banks signed up to a new sceheme to refund customers who are victims of 'Push payment fraud'. The Co-op Bank wasn't one of them.

Push payment fraud is where customers are conned into authorising a payment to a fraudster, believing it is for some legitimate purpose. An example is when the fraudster claims to be from the bank itself and asks the customer to transfer the money to a different account as part of a security measure. While the banks are notr promising to refund all customer victims, many more will be refunded than in the past when the default position has been "you authorised the payment. it's your mistake".

The eight banks are Barclays, HSBC (including First Direct and M&S Bank),  Lloyds (including Halifax, Bank of Scotland, and Intelligent Finance), Metro Bank, Nationwide, RBS (including NatWest and Ulster Bank), Santander (including Cahoot and Cater Allen) and Starling Bank.

Customer Union members asked why the Co-op Bank wsn't on the list. The bank told us in July 2019:

"We’re committed to sign up to the code and we’re progressing this as quickly as we can with the aim of being signed up around September, although we do currently review instances of fraud on a case by case basis and already align to the code in the way that we support our customers.
 
As we were not in the original group that formalised the code we’ve been working to review our current processes and make any adjustments needed to enable us to sign up to the code as soon as possible and we have committed to do this since the code was first announced.
 
Our customers can be assured that we are continually working to provide fraud education and protect our customers from being the victim of fraud or scams and we work with the wider industry to support initiatives such as Take Five to ensure a consistent message is delivered to our customers of what kinds of scams and fraud they should be aware of and what to do if they suspect they might have been a victim."

More details about the scehem in these articles (May 2019):

Moneywise

BBC

More about push payment fraud in this Guardian article.