Right okay firstly, I suggest you read this
Tutorial - Billing and Payment FAQ
Secondly, there are free TRIAL bots on the bot store for a reason. USE THEM. You can use the bot for on average a hour upto 7 hours on trials depending on what the author has set it to. No bot public will ever be tailored to your specific usage unless you ask them (the author) to modify it or private access it for you. It's just a generic bot that will do said activity in a way that it's programmed to.
At the moment, we've had a few issues (not down to the authors) but Runelite and Runemate connections/communication since Runelite seem to do a dodgy update every few days and it throws Runemate off until it's fixed. If you could provide logs, screenshots of the error that you get and contact the author, we could assist you further but at the moment you're raging about something that we can't control because you've not given any constructive information for us to work from. I'm not trying to be a dick here but you need to understand that with no information apart from "I want a refund bot didn't work as expected getting errors" or whatever, that is useless. We can't work from that at all. Tell us what is going wrong, provide information, give us the error, we can only help you if you help us.
I will agree with you on one thing though, the payment system when starting bots do need to be reworked and even us authors have been asking for it for awhile now due to refund requests left right and center. Unfortunately, it's not something that has been approved and set it stone as of yet but it's been requested.
You can see the request where I completely agree with the user.
Request - Charge people fairly for scripts
I hope you understand that we are trying to make this community better for users and authors. Sadly, you can't just blame the authors for everything.
In regards to you stating that anybody can become a bot author, you're right and wrong at the same time. Premium bots are very tricky to get on the bot store if I'm honest, they must meet certain requirements which are checked by the executives of Runemate. HOWEVER. iirc, free bots must meet certain requirements but not as much, since they're free and no user will be charged for the usage (apart from your free hours for the month).