Bank unauthorised transaction.

I experienced an unauthorised transaction from my bank account, On the 19th of August I received R700 from my boss at around 5 in the morning, 2hours later while I was asleep that money got withdrawn and I quickly rushed to the bank. The assistant from the Park station branch called the head office and report unauthorised transaction. I was then given a reference number and told that they'llinvestigate and give me feedback within 8 workings days. On Aug the 26th I got a call from one of their assistant and she told me that according to their investigation, the person who cloned my account knew my pin and hence they wouldn't refund me. I'm still not convinced because no one else knew my account's pin number and I think it's just one of their tricks to rob the customers.