If we are unable to solve your problem during a reasonable time frame (up to 30 minutes) you won't be billed, and what's best, we'll give you a free analysis of the problem and will provide you with further advice how to resolve it, even if not by us, and we'll offer you who to address for better resolution.
If your problem requires more time to analyse, we'll advise you. Based on your permission we'll continue the work and you'll be billed by the hour.