Application of payments.

All payments to be made by the mortgagor to the mortgagee shall be added together and the aggregate amount thereof shall be paid by the mortgagor each month in a single payment. The mortgagee shall apply each payment received to the following items in the following order: (a) Premium charges under the contract of mortgage insurance; (b) Ground rents, taxes, special assessments, and fire and other hazard insurance premiums; (c) Interest on the mortgage; and (d) Amortization of the principal of the mortgage.