Unprofessional behavior, trying to shame me at work to make a repayment!!!

After making arrangements as to when I would be paying back the loan amount that I am in arrears with they keep on calling, sms'ing, and emailing me. The problem is that they have found my work email account and I receive emails from them daily now in my work inbox that my manager also has access to. I have sent them a friendly request yesterday to please stop using my work email and have received 4 emails to my work email in the last 24 hours. That is just plain spitefulness and so unprofessional clearly they are trying to humiliate me at work. I have been a client of theirs for a long time and always paid on time now that I am in financial difficulty this is how they treat a person.