Five mistakes on bill

We dined at the Woodlands Spur last night and when we received our bill we found that there were additional items to the value of +/-R200 on our bill. Incorrect quantities were entered in five instances i.e. 4 x mineral water in stead of 2 etc. When we asked the waiter to call a manager he at first refused and said if anything is wrong he will fix it. We again asked for a manager. A manager then brought a calculator to our table and told us to fix the bill ourselves. We asked him to do it as we had marked the incorrect items. When we left he told us to please call him next time when it happens with no assurance that he will look into the matter and prevent it from happening again.