bad service and lack of customer service

I purchased yogurts form pnp n1 city.. with an expire date in april and a sell by date in march yet when opening it in February it was all gassy and sour... anyhow I informed them immediately about it... they promised me vouchers... too compensate for there expired yogurts and false advertising on packaging... and too this day I still haven't received anything... been corresponding with a Natalie at sonnendal and when I enquire about the vouchers she will just reply it was sent.. it doesn't take nearly 2 months too post or deliver something.... I was totally understanding and patient... there customer service at sonnendal really sucks!