Number change issue

I have contacted them twice to do a number change. I have left my contact details promising that they will call me back. This has happened 3 to 4 times already but they never call me back. It's either you will be answered by a person who doesn't even know how to help you. You can hear that this person is not going to be able to help me by the way the person will be answering, no confidence at all sounding all confused asking each other, you will be even hearing on the background people chatting. Yeah hey, please can someone help me with the contact number I should call to get assistance with a number change. It's not a simswap it's a number change. I want my prepaid number to be changed, to be my contract line. I have a contract number not doing anything just month to month paying for data a minutes that I am not using.

Thank you!