M&S looks to be moving to reposition their incident as a third party failure, which I imagine will help redirect some of the blame (they present their financial results during the week to investors): https://www.bbc.co.uk/news/articles/cpqe213vw3po
Both M&S and Co-op outsourced their IT, including their Service Desk (helpdesk), to TCS (Tata) around 2018, as part of cost savings.