For seven years Anthony Anscombe thought he was paying child support to help raise his son. But not a cent was reaching the boy.

The Whanganui sickness beneficiary is frank when explaining that the birth of his only son was the result of a one-night stand 19 years ago.

Suffering from post-traumatic stress disorder due to a violent childhood, he decided he was not fit to be a father and broke off all contact, but continued to pay child support as his son grew up.

Then, in October, Mr Anscombe received a call from a relative of the mother who told him she had died in 2005. He was then informed that his son, who was living in a foster home at the time, had moved to Australia to live with relatives after the death and had received no child support since.

Mr Anscombe assured the relative that money had been coming out of his benefit, and tried to contact the Inland Revenue Department for answers.

But despite several calls – one where he was told by a call centre worker that the mother was still receiving the payments until Mr Anscombe informed the employee she was dead – he continues to receive letters stating he still has to pay child support.

"He [the call centre worker] said he was going to put a stop to that and I just kept getting all these reminders saying I owed a little bit more money, but they actually owe me a hell of a lot of money.

"Had they treated me with some respect and decency and courtesy I would have moved on, but they've just ignored me."

Although he had not been involved in his son's life, Mr Anscombe said he would have been in a position to assist his son when his mother had died. "It's about men's rights, and lack of, because if I'd been informed of that I could have stepped up to the mark and helped Ben ... the system is broken. How many other guys are paying into a big black hole?"

A department spokesman refused to answer detailed questions about how much money had been paid, what had happened to the money, and what processes were in place to ensure similar events did not happen, citing privacy reasons.

This was despite Mr Anscombe providing a signed waiver to the department giving his permission for them to discuss the case.

Revenue Minister Peter Dunne said he was also unable to talk about Mr Anscombe's situation, but added he was very concerned and had asked the department for an urgent report on the case.