four attempts to use this service, all had problems

I have ordered from them four times in the past three months. The most consistent problem is that they seem to run out of stock on items. I am not necessarily talking about deals, even things at "normal" price. On each order there have been 4-6 substitutions and 1-3 non delivered items, averaging one in six of the products I ordered.
Today the delivery was late. The customer service number is chargeable and I had to wait 21 minutes the first time and 25 minutes the second time. The person I spoke with spoke with a heavy accent, difficult to understand. She was polite but totally indifferent to my problem. She had no idea why the delivery was late and she said she had no way of checking either the reason why or the expected time for delivery. She promised either one of her colleagues or the store manager will contact me. Two hours later nobody has contacted me. The delivery has turned up two hours late, with the usual one in six replacements or not available.
Sadly, I will not use ASDA anymore.