If you have entered into an Alternative Repayment Arrangement on your mortgage you should have received a formal letter from the company stating the agreed payments and the duration of same. Provided that you have adhered to that repayment schedule you should not be getting any arrears letters or correspondence. Paying monthly or fortnightly is not an issue provided that the payments are made by the due date each month. Normally when such an agreement is reached it includes capitalization of arrears! Do you have a written agreement on the revised repayments?