Worst network ever!!!!

I am trying to do a simple thing as an upgrade. The store couldnt help and told me the is a credit control status on my acc that they can't see. I called their Retention department( just as useless as the store) , gave me another number to call *** I was on the line for 33 min no one answers. I want to upgrade can someone just explain what this credit status is .and whether I will be able to upgrade. If not I cancel this contract and go to a service provider