Sarah Champion was confronted by the 23-year-old student during a BBC General Election debate, featuring politicians from all of the UK’s main parties.
He said: “How can you spend money you don’t have? Young people are being burdened with debt, student debt, house prices are at astronomical levels… but Labour wants to borrow even more money.
“So who is going to pay that back? It’s going to be my generation that’s going to have to start paying those debts back.
Sarah Champion clashed with the student during a BBC debate
“Why are you borrowing more money when we are the ones who are going to have to pay it back?”
And as Ms Champion insisted Labour had been “very clear”, the student cut her off, saying: “No. you haven’t been clear.
“Diane Abbott can’t add her sums up, you’re not clear.”
Rounding on the 23-year-old, the Labour politician said: “I’m not Diane Abbott. Can I answer?
I’m not Diane Abbott. Can I answer?
“We’ve been very clear that we are not looking at borrowing money unless it is for capital investment. What we are looking at is making sure that we are completely within our means on the spending that we are doing on revenue spending.
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“We have had that independently verified and to be quite honest, the only figures that are in the Tory manifesto are the page numbers.”
A Labour spokesman said: "Jeremy Corbyn has asked Lyn Brown to stand in for Diane Abbott as Shadow Home Secretary for the period of her ill health."
Snap election 2017: The pictures politicians may not want you to see Sat, May 27, 2017
Protests, fights and daleks, it's all happening as the politicians hit the campaign trail for the snap election
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Jeremy Corbyn during a visit to Hackney Marshes Football Pitches, to highlight Labour's manifesto commitment to ensure 5% of the Premier League's television rights income is diverted to the grassroots game, during a General Election campaign
The news comes just a day before the election and after Ms Abbott pulled out of two major election events on Tuesday due to illness.
Defending his aide, Mr Corbyn said Ms Abbott had not been well for a "couple of days" and was "taking a break from the campaign".
He said: "Of course Diane is somebody that works extremely hard and represents her community very well.
"I have to say has received totally unfair levels of attack and abuse not just recently over many years."
Asked how long she would be taking a break, Mr Corbyn replied: "I'll be talking to her, later on, today – she's not well at the moment."