2l bottles taste horrible! Fix it!

I bought 2 x 2.25 l cokes yesterday from Spar and both of them taste like medicine, I’m not sure if that’s the right term. It hurts my throat and makes it feel like it’s itching. I’ve complained about this before in the small bottles. I’m not sure if you trying a new flavour or something was contaminated but it’s absolutely horrid please fix this. I can’t keep buying cold drink and it tastes like this.