What is the ruling on working for a company that delivers customer account statements to banks, and insurance premium statements, and working for mobile phone companies, knowing that the banks it deals with include NSGB and HSBC and others?

It is forbidden to cooperate in sin and aggression and disobedience to the Messenger; as Allah Almighty says: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression). Based on this, if banks deal with usury and forbidden transactions, it is not permissible to facilitate their customers' usurious transactions, such as delivering their account statements; because it is cooperation in sin. Also, commercial insurance of all types is forbidden, and it is not permissible to assist in it. As for working in telecommunications companies, it is not forbidden in its origin. Based on the foregoing, the predominant nature of the work in the aforementioned company is assisting in forbidden transactions, so it is not permissible to work there unless it is possible to specialize the work to deal with permissible entities, which is unlikely.