Shocking customer service

I lease an apartment from IHS. They are the most *********** business I have yet encounted. My rental is paid via debit order each month without fail, I have not paid their rental fees across the tenure of my rental yet without fail, they send me threatening letter regarding outstanding rental fees, including threatening to black list on the credit bureaus . It amazes me that they diligently place these threatening under the frontt door yet when issues arise such as black mould, they drag their feet in addressing the issue.