All credit card installment business cannot be changed once it is accepted! Some banks also have 24 hours to go back on their word, but there is no way to change it after the time! Of course, if the other salesman cheated you on the phone, you can directly contact the credit card customer service center to complain. Every call from the bank is recorded. If I really lied to you, I can cancel the installment, but the telephone recording didn't lie to you and I can't change it!