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.