Poor service and credit bureau not updated.

Very disappointed with RCS, I paid up my account last year September but is reflection on Credit Bureaus that I’m behind with my account. Logged comply and they said I must supply them with paid up letter which I did on the 4the December 2019 but to date nothing has happened. When I can they just put me on hold for several minutes till o hang up. Wrote follow up mail letting them know how this is affecting my careee but no one seems to care.