Momentum Online shop is *****ing my money

On 16/12/2017 I purchased two Edcon vouchers on Momentum Multiply Online Shop which is supposed to be delivered within 3 business days. Since then I have been following up over and over again and finally received one of the two vouchers only on the 3rd of January which completely defeated the purpose I purchased it for. I have however still not received the second voucher?!? They keep on telling me that they did send it and the more I say I have only received one of the two the more they say it has been done. I paid for something that I did not only not get in time as promised but did not even get at all. I requested the manager to contact me and a week later still nothing. I am complaining here as I am fed up of not getting feedback and service and the product that I paid for!! Very poor service Momentum.