After an MPs' report calls the Child Support Agency a "failing organisation" which may be scrapped, one father says he has no intention of giving the "unfair" agency a penny.
The man, who wishes to remain anonymous, claims he has been relentlessly pursued by the CSA for seven years despite paying out "substantially more" money than the agency has asked for.
The father says he has already paid thousands for his children's upkeep
The businessman, in his early 50s, claims he had to deal with the trauma of his wife leaving him for another man and was then unfairly pursued by the CSA.
He believes the agency does not take into account the acrimonious nature of divorce and the needs of both parents.
He claims that at first his ex-wife made it difficult to see their children.
"She always wanted to see far more of the children than I did," he told BBC News.
However, he said that over the years the children, when not at boarding school, have spent around half their time at his home and the rest at his wife's.
"I have an absolute clear conscience that I have fufilled my obligations to my children, and I don't begrudge them a penny I have paid, but I refuse to fund my ex-wife's lifestyle, " he insisted.
He claims his ex-wife can afford to run a large house and expensive holidays, despite telling the CSA she only has an income of several thousand pounds a year.
The businessman feels the children's maintenance money has already been settled via a capital settlement following the couple's divorce several years ago. He said he has paid for many outgoings, as well as paying thousands of pounds of school fees.
He added that he has been to three or four tribunals to try and get the money the CSA asked for lowered, even producing evidence that his wife's income was more than she claimed.
"The CSA is grossly unfair", he said. "They have never disputed her claims or made any effort to check them out.
"That's why people won't pay - because they think it unjust, " he said. "I have never given them a penny, and don't intend to."
He says his own experience promoted him to volunteer to help other men, and he found that "in 99% of cases" the CSA and court system favour the mother.
"They consistently make the woman the parent with care, which makes you top dog, he said.
"The system assumes women are better parents than men, which is totally discriminatory and actually illegal".
He claims the CSA doesn't consider many factors, such as cases where the woman earned considerably more than her ex-partner.
"Not only is it completely discriminatory but the rules are unjust," he said. "What happens if the rules are unjust is that people ignore them."
He says that as well as letters, CSA officials have phoned up in the evening and were rude and "perfectly unaware of the circumstances".
The involvement of the CSA had increased the growing bitterness between him and his former partner, he said: "It makes it very difficult for me to have any sort of relationship with my ex-wife and to talk about the children. I never speak to her."
He added that "in theory" the CSA was a good idea but that it was fundamentally flawed. He wants to see an overhauled agency with a belief that "parents have equal rights" at its heart.
"I've no time for people who run away from supporting their children.. but the CSA goes for the soft target, the dads who want to take a role. It makes little effort to contact the fathers who aren't around."
A report by the Commons work and pensions committee pinpointed problems with the CS2 computer system as contributing to a huge backlog in application being dealt with by the agency.
The father added: "It is very little to do with the computer system, although I am sure this has contributed. It's to do with the rules which are manifestly unfair, and is the reason people ignore them."