1) Sending a deposit is pointless. There are providers who will see you without it, and you can go to an agency who doesn't require it. Zero point to send a deposit, ever
2) Getting upset at a SW is pointless. I understand that as a monger, if you have a sour experience, it's very annoying.
My method to deal getting an unsatisfactory experience with a provider is simple. I just never see her again, that's it.
I remember her face so I'll know who she is. Therefore I just never book her again. It's really that easy