Cell C Airtime *****

I bought R10 airtime voucher from my local tuck shop. The voucher was sealed I had to tear the sides to open it. I tried numerous times to enter the air only to get the voucher invalid response. I call the call centre. After check the voucher details (seriel number, last five digits of voucher number) The agent confirms the voucher was legit but the airtime was already used by another number he couldnt confirm. He then informs me that Cell C does DUPLICATE voucher numbers and he couldnt help. Tells me to take the voucher back to the shop for a refund. So the Somali shop owner goes " HAHAHA No my friend, No refund for airtime!" This was the last straw from Cell C. Porting to Vodacom!!!