Citibank Mortgage Complaint

Citibank Mortgage department,

Conventional adjustable mortgage (ARM) Loan servicing, payments, escrow account California

I Have a mortgage loan with CITI Mortgage. Since it is a variable loan i have been making $3000.00 principal payments to reduce my balance. I just to include the additional principal with the payment and write down the additional principal amount on the coupon. Several times they misapplied the payment and applied it to the interest and the escrow amount. i have called them many times and it takes a lot of time to get them to correct their mistake. i then talked to a supervisor and was told to make a separate check. I started doing that but every once in a while the payment is miss applied. I dont know what else to do to get them to stop miss applying my payments. If it is happening to me it must be happening to other borrowers who may not look at their statements carefully.