That spells is very poorly written, in best possible case it can produce strike of minor bad luck for two of three days, with possible headache lol
And even that in case person is very skilled, so it would be really direct energy atack more than spell
But a word of advice to You , even though "famed" karma and Law of three are not impecable and strictly bounded to specific systems/relligions what You saw is what You'll reap.
In my oppinion it is tremendous lack of manners , and sign of mental weakness to punish someone via magick ( if the object or target if You will, are not a practitioner themselves ) , even more for silly reson like Yours.
Be creative there are many mundane , legal ways to do what You aimed
Magick should not be looked at as solve all :D