Minimize maximum duration of booking and maximum bookings per day

Hi everybody
I am using MRBS (latest version, 1.4.6.)
I want to be able to allow users to book up to x hours y times a day (in particular, up to 3 bookings of 1 hour). do you have any advice?
Thanks everybody in advance

PS: i found something that seemed to do what i wanted here:
General discussion of MRBS (Meeting Room Booking System)
The maximum bookings per day works fine but i cannot limit the hours of each booking. Maybe it does not work for my particular version? or i am not putting the piece of code in the right place?