Miladys Account

I paid my account on the 15 February 2019 and in April I got phone call from MBD Attorneys for collectios.I told them that I settled my account but they never stopped calling and texting me. I went to the shop (Miladys)in Jeffreys Bay and the lady I spoke to said she was not able to help me because my account is locked. The only thing I need is a paid-up letter. There are things that I can't do because it says my account is in arreas. Miladys I paid you please clear my name and ask MBD to stop calling me,This is harassment.