C***** poor customer service

I purchased 2l C***** full cream milk dated till 13/10 - on using it on 11/10 I noticed it tasted odd like it was starting to sour, so I sms's the number on the side of the bottle... No response, so I phoned the customer care number on 12/10, after being on hold for quite a while I was given the option to leave my details, at the end of the day a lady called me back, I explained and gave her all the details on the bottle that she requested. She advised that they would send me a voucher (I didn't ask and she didn't say when) So today 17/10 after having heard nothing further I phoned the number she called me from and spent 2&1/2 minutes explaining all this again only to be told I must phone the other number!? Keeping in mind this is all on my cellphone bill - I've probably spent more in airtime than the milk cost! Very poor customer service :( I still have no idea if the voucher will materialize or not and if so how long this process takes.... Very disappointed!!!!!