Seems odd. If you are not in it, better stay away. If you are still in it, pray that it last as long as possible.
Please be mindful about "investing" with HashOcean. It may be legit, it may not be. But I am sharing my observations. Good luck.
You have right! Here is banner that they have been using in last year:
https://hashocean.com/promo/
and they are using this banner till now. It is ROI in 4 - 7 months.
Where did you found information about 2-3 months promises?
60 days investiment back months ago, when the BTC was cheaper. 0.005 BTC payment each 20 days, after 60 days 0.015 BTC. Average investiment 0.014 BTC. And using 15 GH/s for free on the first month, faster.
But now the BTC is more expensive, I think need to wait more months, increasing the risk to be scammed in this middle time by the Ponzi scheme.