Petition Stop M.P.s using public money to buy properties then profiting from their sale.

According to the Daily Telegraph John Bercow was able to claim public money to pay off the interest on his mortgage. He then sold the property at a huge profit. He is allowed to earn rent from his present property whilst living in a 'grace and favour' property himself. How is this fair to the ordinary taxpayer especially those who are having their properties reclaimed because they have lost their jobs and can no longer pay their mortgages?
I am suggesting that on the sale of such properties the public money used should be paid back first and then at least half of the profit made should also be put back into the public purse.