Unfair billing

I have been banking with standard bank for a few years up until 2013 and i changed my bank due to money being deduct from my account with no explanation. Now years later im getting calls and messages from lawyers saying i owe standard bank money, ive called head office and the lady send a mail to parow branch its been weeks still no feed back as to why i owe money messages is not even being sent to my private number its being sent to a company phone wht thousands of people have access to so its getting embarrassing aswell. If u check my bank account that i had with u its been inactive for several years now my question is why couldn't the branch call me to say i owe money for whateva reason y must lawyers call me how are u being fare towards people that even think of banking with you like that? Ive called the branch no answer and i dnt know what to do from here right now....