The bare minimum they can do is nothing, offering a refund on all of the delivery charges is an important step above, but offering a refund on the entire service so far?! That's quite an extra mile.
I'm afraid I didn't make it clear. I meant a refund for the most recent $99 auto renew charge that had changed the terms of service without notifying the customers.
No, Instacart made an agreement which they need to honor more faithfully. If the 71 customers had decided to change the terms of a business agreement similarly, their accounts would probably be closed and referred for debt-collection.
The fact that Instacart is a tiny startup has no bearing on whether they should honor their agreements.
What is the agreement that they are honoring in this case? They didn't have a plan for further $35 subscription, people were either moving to the more expensive subscription or canceling.
Allowing the customers who weren't aware to retrospectively cancel and also keep any value of the service they already used seems fair.
You can repeat that until you are blue in the face if you like. That won't make it a true. It is ludicrous to modify a business agreement without actually giving notice, and expect to keep the proceeds of that mistake.
If they no longer want to offer a free tier, they're free to end it. I don't think anyone is proposing otherwise. They are not, however, free to unilaterally move people to a tier that costs money and start charging them without an explicit agreement.
They've offered refunds on delivery charges and a full refund on the Instacart Express subscription fee for people who don't want to come along with them to their new pricing model.
Doesn't really matter. The fact that they charged without permission is seriously wrong, and I don't see them owning up to that. They seem to think their mistake was in not notifying people well enough.