Stupid people working in the creditors dept

Builders creditors dept keeps on harrasing me and my husband for non payment even though payment is made on the 28th of each and every month, when we call head office to query they keep telling us that the account is up to date and nothing is outstanding, just for the stupod idiots in the ceeditors to keep calling as payment doe not reflect on their side, so Builders how does it work that your system is upfated at headoffice but not at the creditors dept, i keep asking for a settlement amount but i never get the mail they keep promising to mail worst people to have an account with