Lessen space between header and surrounding content

Based on some help with spacing on another topic, I’ve tried a few options to fix another case of having too much space above and below some header text.

Specifically, I want there to be less space for the H3 tags on the page noted below where it says “ADD ONS / USAGE PRICING” and then also where it says “PHONE PURCHASE / LEASE OPTIONS”

http://www.o1.com/hosted-pbx-plans/

I tried using the following but it hasn’t made a difference:
.avia_textblock h3 {
margin-top: 0 !important;
margin-bottom: 0 !important;
}

Can you advise?

Thanks,
Tom