Pepsi co *****ulent customer care

I bought 10 boxes of Pronutro and Pepsi Co said they going to refund me. I have sent numerous emails requesting my refund and Pepsi co said they send me a voucher. I asked for proof and now they no longer reply to my emails. Natasha Young, Achmad Bassadien , Mogamat Lakay from customer care no longer answer my emails as to where is the voucher they said they sending.