Borrowers looking to refinance their mortgages are choosing alternatives to the big banks, according to one of the country's biggest brokers.AFG said the big bank share of mortgages written by its brokers fell from 72.2 per cent in August to 64.1 per cent in November - a post-financial crisis low.AFG general manager of sales and operations Mark Hewitt said this move had been driven by "refinancers" looking for lower rates.Hewitt said another factor was that the big banks had pulled back from the investor market, with their share of that segment falling seven percentage points over the three months to November.Some of the lenders to gain share with AFG brokers include Suncorp, AMP Bank, Teacher Mutual Bank and ME.The non-major with the biggest share is Suncorp, which accounted for 4.8 per cent of the loans written by AFG brokers in November. ING Direct's share was four per cent, AMP Bank 3.3 per cent and ME's 2.9 per cent.