Are all of these bots actually subject to a charge or are there also free bots available?
Since you've tried multiple bots, do you have any recommendations?
The first bot I used was a self written balancing bot (it tries to balance out fiat and BTC based on a rate, e.g. 60% / 40%). But it wasnt capable of any trading strategies so I tried some free trading bots out there. The by far best bot is "Gecko Trading Bot" in my opinion. It is very easy to set up, has a self-explanatory UI and a lot of trading strategies built in. I would give it a try if you are interested in it. Just load your favorite exchange with some BTC (I was trading 0.1 BTC back then) and let Gecko trade. Some of the trading strategies require a lot of historical data, so it may last 1-3 days until Gecko trades the first time!