A non working Data sim card

Mondo (Rewardsco) sent me a MTN data sim card in January 2021 and more than a year later, I've not heard from Mondo again and now they handed me over to a debt collector for a data sim card that doesn't work and I never used. How does this organisation make customers liable for a product that doesnt even work? Ridiculous service and a call centre that charges you airtime and can't even assist you