Block 2 hours time-slot from server local time

Hello world !!

We use appointment+ for a "to-home-service" (we go to clients houses)

Let's say it's 12h30 pm... a client can book an appointment in 30 minutes... It's impossible for us to go there is 30 minutes, we need a 2 hour frame. So if it's 12h30pm... the next availability should be 14h30 and later...

I thought the "Appointments lower limit (hours)" option will worked but it's not : http://awesomescreenshot.com/0fd2im6qe3

See this screen shot : http://awesomescreenshot.com/0e72im4w7b

Thank you.