Allied Collections Services Inc. they added money to my balance more than once, they wont tell me personally why Las Vegas Nevada

i had a medical bill that went to a collection agency, i agreed to do monthly payments, the first 5 months i noticed tha my balance was not going down as it should have, i noticed that they had added more than once money to my account, as much as $100.00 a in a month, that is a lot when the monthly payment is $133.00 . i called and talk to the manager and she gave some explenatios that made no sence, i asked to see her personally so that she could explain why my dedt was not going down as ii shoul have, and she refused. i said i whould stop payments , and she said she would garnish my paycheck if i stopped

Ricardo
las vegas, Nevada
U.S.A.