Incompetence at its best!!!!

After receiving a letter that my loan is completely paid off,a loan installment is debited from my account again and when questioned Capfin consultants then tell me it's the interest on the loan, why send a letter of completion then if it was not complete, these people are absolute idiots and *******, they do not share what the WHOLE loan encompasses and does not give two ****s about their clients, i will absolutely never use Capfin again and really hope that anyone will think twice and ask every possible question before stepping into a binding agreement with them.