The ka as 4 bolts at the back of the back plate they hold the drum on no need to undo the wheel bearing nut you can damage the bearing. Remove these remove the drum complete with stub axle and clean/inspect rear shoes and wheel cylinders, The drum may have a lip on rub this down nice and flat with emery roll that fits in your drill. Then adjust shoes up to suit, your looking for approx 4 clicks on hand brake not less than 4. good luck mate.....

On our 2008 Ka, I found one rear brake not holding very well on the handbrake. The cable was pulling through OK when the brake lever was pulled on, and all the levers and adjusters were free, but the cable was holding the shoe lever off its stop. The cable plastic sleeve had effectively ruffled up, preventing the cable from returning fully. New cable set required and it appears they are readily available.

It should never be necessary to manually adjust. Make sure that the shoe lever is resting against the shoe web. If the cable is holding it away from the web, the auto adjusters can't work properly. The same applied when cables had adjusters - 1970's - if the cable was adjusted too tight, proper adjustment at the drum was impossible and the performance could be erratic.