Ah...diet coke addiction is one on its own.I will chip in and say anecdotally I very much believe that low sugar/sugar free drinks are very addictive as I most definitely have a diet coke problem and if you've ever met someone who likes diet coke they're often always a little unhinged about it
My opposite number in care work listed it as her one addiction, and she had it bad...no substitute was acceptable.
Used to buy it by the slab of cans, and had bottles stashed away at home.