BAD CUSTOMER SERVICE

They have offered me an overdraft of R8000 but once I have used it within a month they want it back yet they have said I can use it be pay it later during the same week I get a call from their lawyers demanding me to settle off the account or else they are going to close the business account. So why were they offering such yet they know within a month they will want their money and include lawyers. I have had FNB account (business account and personal) for more than 5 years but now I might consider moving to other banks because I can't be treated like this yet I trust them with my money every month.