Yesterday they sent me a text with a code because it was the first monday of the month, I guess. But I used it, and today I see that I have been charged.
The weird thing is, I've been renting a lot and a couple I actually paid for haven't been charged yet! I guess I shouldn't be complaining, but i t just seems unorganized.
Also, do they charge on the day you return it, or the day you rent it? This might resolve the problem.