I think Tesco should have paid the extra 160 quid and just uprated their free version of Avast to Premier.
Tesco refunds £2.5 million pounds to 9 thousand customers after bank attack. http://www.bbc.co.uk/news/business-37915755
They think the "Retefe Trojan" may have something to do with it. Interesting, because banking trojans have become less of a threat in the last years. http://www.welivesecurity.com/2016/11/10/tesco-bank-not-alone-targeted-retefe-malware/
A much more convincing analysis of the competing hypotheses here: http://withoutfire.com/2016/11/was-tesco-bank-hacked/ Much closer to the truth. In my opinion
Tesco Bank faces £30m mega-fine over 2016 cyberattack September 25, 2018 https://www.theinquirer.net/inquire...-faces-gbp30m-mega-fine-over-2016-cyberattack
Tesco Bank Fined £16m After 2016 Cyber Heist October 1, 2018 https://www.infosecurity-magazine.com/news/tesco-bank-fined-16m-2016-cyber/
Too right, Tesco have recently announced making a profit of £1.64bn on sales of £57.5bn in a ninth consecutive quarter of growth.