Those that have used Instacart, were you satisfied with this service? Were substitutions made and were they appropriate? Instacart costs half of the other grocery delivery services I've looked into (Garden Grocer and Dizzy Dolphin). I've been happy with GG and DD in the past but the mark up on the prices is quite high. However, if it's best to pay those prices for the customer service aspect then I need to decide which is best!