I know exactly what you mean Op - I do my elderly Dad's shop and have almost been caught out with this, because you assume the total is the food total, not the amount with £5 delivery and £4 minimum basket charge added!
There's something wrong with the Asda site just now - for eg. if you put "ready meals" into the search bar, it tells you there are 38, then it lists about 5, then the next line is called "products popular with others" (or something like that), and it shows all manner of shite unrelated to ready meals, things like washing up liquid or laundry tablets. What the fuck? The only way to see all the ready meals, is to find one that's on the £8 for 3 deal, then click on the little red square that will show you all meals in the £8 deal. 🙄
You also can't change your slot time any more - you have to cancel the shop and start again. Then when you start again, it asks if you want the same shop at a different time - which would be helpful, however, it restores your basket with only one item of each - so if you've previously ordered 3 litres of milk, it will only put 1 litre back in.
Also, the price per 100g is often miscalculated.
It's a shit show.