I really can't fault Ocado.
I have never had any missing items or substitutions (unlike other delivery services) and I love that you are notified at the point of order if anything is unavailable.
Deliveries have always been within the delivery window requested and on one occasion they even called to see if they could deliver early.
Delivery drivers are always friendly and willing to bring the bags into the house.
I love the flash sales at checkout as well as new customer an loyalty bonuses.
Like I say, I can't fault them and only have nice things to say!