Suddenly the website won't allow me to book my next slot, saying "Delivery slots for these dates are fully booked". What's going on ? Is it only Tesco's priority slot system that are affected ? I have taken the precaution of booking ( my first ) delivery slot with Sainsbury, and on first sight it looks as though they have better availibility. [ We had enough of a problem in getting Tesco to recognise that many customers were elderly or disabled, but not covered by the government's 'vulnerable' groups ].