Padding doesn't appear to be working

Hi,

We are tesing appointments+ here:

http://www.aspiringsolicitors.co.uk/beta and when I check 'Padding' either on the 'Service Worker' or on the 'Service' itself it doesn't add a 'time space' between one time slot and another, but actually adds time to the 'Time base (minutes)'

So we have 15 minutes and if I add 5 minutes of Padding, I get 20 minutes in calendar.

Can you help?