Sorry, but we are just other members like yourself. We do not have access to your account details, nor the authority to make changes on your account. We can only advise you as to how best you can resolve your problem.
You need to turn off your Auto top up on your Payment details page here:
Click on Change at the end of the line that starts Auto top up, then untick the box, and make sure that you click Save.
It might be wise to check to see what your airtime credit has actually been spent on. To do this, look at your Usage statement here:
Note that this can be a couple of days behind, so you may need to wait a day or two to see your latest usage.