I think verper can chime in better here, but some of the Salifert Alk tests were bad. I'm not sure of the batch numbers, but you may want to check your batch number first.
Next, try to do several water changes over the next few days. I'm not sure of how harmful high alkalinity can be, but I know it's not beneficial.
When I had my alkalinity drop, I had to test several times over a period of about two weeks to find out the right amount of alk to dose. Just because a bottle says you should dose x amount, doesn't mean that's right. It can vary based on the frequency of your water changes, the amount of corals you have...and even on other chemistry of the water.