No response re Refund

I used Zulzi for a grocery order and delivery for the first time on 28 April 2020. Groceries were delivered within a couple of hours, but many items on the order were not delieverd. I emailed Zulzi the same day to request a refund with copies of the original order and the actual invoice of the delivered items, and requested a refund. To date they have not acknowledged my email or refunded me R260.36. Very very poor refund service