One of the most obvious non-mechanical failures of the Volta system is the linking of repayment or redemption to a specific location. Containers returned at any given location must have their refund paid through that location. Where recurring machine failures at Shop A necessitate recycling through the facilities of Shop B, the consumer is now tied to Shop B for recompense - even if the consumer has no desire to frequent Shop B.
Receipts issued from any machine should be redeemable at any location that charges the initial deposit. This will undoubtedly create more administration issues for retail establishments but it will remove the burden from the public in general. This change would also allow the placement of recycling machines at locations convenient to the public but unaffiliated with any retailer.
There is an official app that advises the location of Volta recycling machines. At best, after the first time using the app it becomes of little or no benefit. The consumer has seen the location of machines. And that's about all the app really does.
Implement a system that advises the operational state of each machine, in realtime. Offer alternative information about the nearest working machine. Allow consumers the option to be notified when their preferred machine has gone out of service - or potentially of more benefit, when it has returned to service. An additional option could advise when a machine has been unused for a period of time, signaling to the person waiting to return containers that it might be a good time to head to the machine.
Cans get dented, labels on plastic bottles get ripped or faded to the point where the scanners in Volta machine can not process the barcodes. This leaves the consumer no real recourse except to dispose of the containers without the ability to reclaim the deposit. Someone, somewhere has just pocketed that deposit. It doesn't matter if that lost deposit goes to fund the Volta system - the consumer is still out of pocket.
Require retail establishments to personally accept damaged vessels and refund deposits after inspsection by retail personnel. For fairness, these establishments need only accept damaged containers that are of the same product lines that the stores sell.