Cell C nonsense billing and service

Cell c has charged me almost R850 extra on my monthly bill, I queried this in their mall of Africa branch and besides having to wait over 25 minutes for assistance (the only person who could help was Mique and he was out so I waited almost half an hour for assistance even though there were 5 staff members on the floor). Mike finally arrived and printed the bill for me, didn’t even check what I was querying, he hands me the bill after pressing his keyboard aimlessly for another 15 minutes. Again I asked what the additional costs are. From his calculations my bill should only be R280 more. PLEASE EXPLAIN WHAT THE ADDITIONAL CHARGES ARE!