Receive all of Standard Bank's Cipro calls

For 5 years now, our company receive tel calls from very very irate clients. They phone Standard Bank and then they get transferred by Standard Bank to CIPRO. BUT they have Cipro's number incorrectly in their system, so every call that they transfer gets through to our company. This after some clients have been holding for 30 min. We get screamed at that we HAVE to help. Well how are we suppose to when we are a completely different company with a tel number one digit different from CIPRO? We have tried how many times to trace the origin of this problem, I personally have phoned head office and tried to solve the problem in the IT department. No luck. Even the branched get through to us and no one cares enough to sort this out!