Worst customer service experience

On 31 Jan i redeemed an investec voucher for netflorist to purchase a birthday gift for delivery on 1 Feb. I created the cart, and input the voucher code, i then changed my mind on the gift and cancelled the cart. I then created a new cart with the updated gift upon inputting the voucher code again, the site said the voucher had already been used. I cleared cache and tried again and same error.

I reached out to the customer service team at netflorist and to this day, with numerous emails back and forth netflorist refuses to take any accountability for the error thats created bu their platform. Theyve even been telling me to go to vodacom and investec to resolve meanwhile the issue lies with them. Zero accountability, zero care for how this has impacted me and the person who i was purchasing this gift for.