Looking For Software Can you help?

[miltonhork]

Hi guys long time PB supporter new to the forum

I am a computer repairing person in my part time life.
I am looking for a program. That I can install on my clients computer that will lock out there OS after a set number of days. If there ass doesn't pay me. i.e. I bill them for services rendered. When they pay I will send them the passkey/word and there computer is back to normal. Any suggestions if so, im or post would be greatly appreciated,

I love the bay. I sent those drunk sweds money, hope there ass stays out of jail they have made my business and life much-o better.