I had the same issue. It’s working now: they recently added GPT-4 to the model drop down in ChatGPT Plus. Current limit is 100 queries per 4 hours.
It will still respond as if it is based on GPT-3 because most of its knowledge cuts off at Sep 2021, but it’s outputs are noticeably better than those of GPT-3.5
It will still respond as if it is based on GPT-3 because most of its knowledge cuts off at Sep 2021, but it’s outputs are noticeably better than those of GPT-3.5