Housing benefit will be reduced by # 1.8 bn per year by the end of the parliament, with weekly payments capped at # 400. (channel4.com)
Payment caps don't limit the amount of interest the lender is earning, so they may cause negative amortization. (banklady.com)
Because payment caps limit only the amount of payment increases, and not interest - rate increases, payments sometimes do not cover all of the interest due on your loan. (mortgage-x.com)