The regulator says that a loan is unaffordable if you couldn’t make the repayments without borrowing again. This could be borrowing from the same lender, from someone else, getting deeper into your overdraft or by not paying priority bills such as a utility bill.
So even if you always paid your Provident loan on time, it could still have been unaffordable.
If the lender should have realised the loan was unaffordable they should not have given it to you – that was irresponsible lending and you should get a refund back of the interest you paid.