Checkers Hyperama frequently fails to deliver specials prices at the till point

Why does this keep happening? It's a frequent experience that the price displayed in a Checkers/Hyperama flyer delivered in my newspapers (The Star and Caxton's Germiston City News) is not programmned into the central (?) system out of which the till points operate? This frequently occurs with advertised wine specials and has now been the case with a Beacon chocolate special displayed in the flyer valid from Monday 1 July to Sunday 7th. Same shows any 2 Beacon 80g chocolate slabs for R19. In the Edenvale hyper on 6th the Beacon choc slabs on the shelf carried a specials ticket stating 2 for 20 but when rung up they show on the till slip as 12.99 each and cost to me 25.98. It ****es me off that so often in my experience, the specials prices are not app**** at the till and I ask why this is the case? Besides inconvenience to customers whilst noticed discrepancies are rectified, it's also counter-productive for till and supervisory staff. Surely its not too difficult to ensure that all specials pricing is updated in the system by the time that such specials 'go live'?????