***** Schweppes Diet Tonic water

I have called Coca-Cola 3 times to report their Schweppes ***** diet tonic water! Something has clearly gone wrong in production and they've produced something that tastes like ****** ale/tonic water/lemonade mixed, with a revolting chemical flavour, even the colour of it is slightly off (yellowy, brownish of varying degrees) They have collected and replaced 3 lots of this weird drink from me but I keep on getting bottles of it from my local Pick n Pay, atleast 1 out of 3. I have however given up calling them. Surely they should recall it!!!!! What worries me most is how chemical is tastes/smells and could this be harmful?