Can a poor application of driveway sealer be corrected?
A photo would help identify other ways of fixing the problem and identify what kind of sealer was used.

But in general as it has been applied to thick the only way to fix it is sand it down (or chisel it away if possible) until it is nice and smooth. If any deep scratches happen during the removal process you should fill it with something that will bond to either the driveway or the left over sealer.

You will then have to re apply it in the correct way.

Trying to apply more on top of the already badly applied could be an option but I would not recomend it and could be more difficult than trying to flatten /remove it.

Be sure to use some sort of industrial sanders or get some other profesionals in and the sue the other company for bad workmanship