Some people are unbelievably selfish.
Selfish in what way?
From the look of it, OP placed an order and than realised it wasn't needed so - following Ocado's instruction at the minute - emailed to cancel it. That cancellation didn't happen so the delivery was attempted anyway. The OP then rejected it and came online to complain.
No indication the OP was rude to anyone. Just that they rejected the order. It might not be the way you or I would handle the situation but it does not make the OP the worst person alive.
Some people may well be able to afford to give away a week's worth of shopping. Some may think quick enough (and be able to afford) to accept the order, keep what they can and give away the rest. That's a lovely idea and act, but not doing so is not the crime of century. It's not at a level I would call selfish to the point I cannot believe it.
Being furloughed is shit - how do you know the OP hasn't been and that's one the reasons for cancelling the order?
Having to field the phonecalls you did is shit. But the OP did not place those calls and is not responsible for how rude those people were. The OP may well also have a similar job. Or no job at all.
Yes, Ocado are trying hard in difficult times. They are mostly succeding. They are also putting prices up and making more profit now than they do at Christmas. I feel for their staff but the business itself is not being reproach.