Gum company a bunch of *******!!!

Gym company are a bunch of *******. I have cancelled a membership in January 2018 and received a confirmation that the membership was transferred to another member. I keep receiving threatening calls and messages that my account is overdue. This is the last straw as they are not listening to me. I received another message that my account is over due and ot will affect my credit record. I DARE YOU GUYS TOO **** up my credit record this company will get sued and I that is a promise!!!