1. Bank of Communications credit card installment fee rate: 0.72%/ period (charged monthly);
2. installment fee = installment principal * installment fee rate =3000*0.72%=2 1.6 yuan/period;
3. Monthly repayment amount = installment principal/number of installments+installment fee. = 3000/12+21.6 = 271.6 yuan/month.