First you even said that vote system was perfectly working before the hwid. Meaning his vote system is just fine.
The fact that your project is fcked up and the hwidh method is not implemented or not working properly is not Kara's problem it's yours. If you paid him for this work making the hwid working properly and he didn't make then yes you could say he did not complete the work but now you're wrong.
And the fact that he will give you money is even more wrong. You got what you paid, pay more for the hwid or simply find a solution on your own, it's not Kara's problem neither his vote system problem.