weight issue

I travelled from Jhb to darussalam with my wife & 4 kids (ages: 8, 5, 2 & an infant of 4 months). <br> As per the info we were given when booking online, we packed accordingly. Thus carrying hand luggage of upto 7kg per paying traveller as allowed (all the hand luggage dimensions were within the allowed limit). Therefore, no need to check in any luggage. After well spent holiday, on the return journey, as per the info on the fastjet website as well as the travel smart in-flight magazine (issue 12 October - December 2015..page 62) we packed accordingly. carrying hand luggage of upto 10kg per paying traveller. We were the first in line to check in as soon as the check-in opened. To our utter dismay we were told that we were overweight & that we would have to reduce our hand luggage weight & check in the excess weight at a premium. Failing to do so, we would not be allowed onto the flight. All this repacking & weighing had to be done at the check-in whilst travelling with 4 children who were also becoming frustrated! We ended up being the last ones to check in and even the last to board the plane & as a result we had to haul ourselves & walk all the way to the plane over the tarmac! !!!