Co-op stores continue to struggle with stock availability after a cyber-attack, recovery expected by the weekend.Shoppers facing empty shelves, especially in rural areas; Co-op working with suppliers to restock stores with essential items.Hackers accessed customer data from Co-op systems, no financial information compromised.M&S also affected by cyber-attack, facing possible significant fines and loss of sales; expected to claim up to £100m from cyber insurers.