Bank and credit bureau score differ

Credit score at Bank and actual credit bureau differ and Nedbank does not have a department to explain difference. I have been struggling to find answers and Nedbank staff arrogant speak to you like your brain is a peanut but the question is how can Experian report show your updated score while bank stay the same for 2 months. Worse is nobody in call centre or Client feedback process is helping. I don't know If call centre use outsourced employees but it's a constant can you hold please situation as if they are not equipped to answer the query.