Sasko - bad customer service

I bought Sasko Wholewheat rolls which were still raw and gooey inside. I have emailed, phoned and whatsapped the holding company, Pepsico with pictures, details etc, on numerous occasions. Each time they say they have escalated the matter, and I would receive an sms with a replacement voucher. I still have not had the voucher. This has been going on since December last year, and on principle, I am not giving up on this. I have spent a lot on cell phone calls to try speak to someone in charge, but to no avail. I am not a happy customer at all. Their customer service is atrocious. This company does not even deserve one star for their service.