The statement came after Provident repeated its future performance targets in a bid to fend off the £1.3bn takeover offer that NSF launched earlier this year.
In an attempt to convince shareholders it is on track to turn around its performance, Provident said on Friday: "We are confident that, through our clear strategy and our complementary, synergistic and industry-leading businesses, we will deliver an attractive investment for shareholders.
"As we transition to a model in which Vanquis Bank is the greatest driver of growth, it is appropriate that our return metrics are fully reflective of this."
The group told investors that it aimed to deliver return on assets of 10% (consistent with a return on equity of between 20% - 25%), receivables growth of between 5% and 10% per year, maintain dividend cover of at least 1.4 times and a “sensible” buffer over the Prudential Regulation Authority’s total capital requirement.
Provident issued a clarification on these targets on Tuesday as more than half of its shareholders have backed the offer from NSF, which is run by Provident’s former boss John Van Kuffeler.
In response to the update from Provident on Tuesday, Van Kuffeler said: "Provident's ability to deliver on its promises remains uncertain: the business is not performing anywhere near its potential and 'more of the same' is not working.
"This is reinforced by the clarification Provident has been required to make this morning regarding its future performance targets issued only last week.
"Change is required and the time for such change is now. As we approach 15 May, we urge all shareholders that have not yet accepted our offer to do so as soon as possible."
NSF pointed out that Provident's trading update on Friday stated that the Vanquis bank's rate of increase in delinquency has remained consistent with the first quarter of 2018. It said this "presumably means that delinquency at Vanquis is continuing to increase, a matter of considerable concern, as Vanquis accounts for the majority of Provident's profits".
NSF also higlighted that customer numbers at Provident's troubled home credit business have fallen 15% over the past year. The business remains loss-making and will not deliver profits in 2019, it said.