I started getting letters from this sham company r...

I started getting letters from this sham company regarding a Working Tax Credit overpayment that I had already proven to the HMRC to be an impossibility.

I threatened to report them for harassment. They sent me an email then not bothering to address to me personally so I didn't bother to respond..

If you get any letters from these idiots just ignore.

They are just a debt collection agency with no legal powers - just a few half baked bully tactics.

Never pay them any money. They don't 'own' the debt so just sort it out with the original creditor and keep the proof.