Invalid unique codes

Good day. About 3 days ago I purchased 4 cans of 30ml cokes as there is a competition running. After several attempts the unique codes does not register and comes back as invalid. I tried all 4 codes with no luck. I logged the query online and up till today no feedback. I got an auto response after my enquiry with a ref# ********** 2 but nothing more. This is not acceptable as I got charged for every attempt at entering their code. I feel this is a cheap way of getting customers to purchase their product with **** codes hoping customers will just purchase again until a code eventually works. I requested the cans to be collected from my house with full refund as well as compensation for air-time and travelling cost to and from the retail store where I purchased the product. I need a response please.

Thank you