But Mr McDonnell corrected the UKIP candidate before a further question was asked by him.
Mr McDonnell went on to explain all candidates were contacted by Hayes FM but Mr Dixon was adamant he had not received contact.
However, things started to heat up when Mr Dixon said his Labour competitor "plays the victim card".
She said: "I was informed by email, and then again on the day, by Hayes FM that all candidates were invited to take part in the radio show."
But Lib Dem candidate Satnam Khalsa took part in the Hayes FM debate with a phone interview.
She said: "The Hayes FM presenter did a very good job. I have no issues with the handling of the programme. In fact, it was a good opportunity to discuss the concerns of the people in Hayes and Harlington and the UK."
It is unclear how Mr McDonnell responded to the rant overall, when a further tweet by Mr Dixon claimed he had been blocked.
Mr Dixon thanked the previous Labour MP for forwarding on the original email so he could speak on the Hayes FM show.
He later told getwestlondon: "There was an issue with the station sending an email invitation to an incorrect address, which was a genuine mistake on their part but quite understandable as it was using a format that many UKIP candidates use.
"They tracked me down promptly after the twitter spat and were extremely quick in getting me on air and fulfilling their impartiality obligations."
All Hayes & Harlington prospective parliamentary candidates and Hayes FM were contacted for comment.
Still unsure which party to vote for in the General Election? Our comprehensive guide has all the answers.