Installment plan

I have been getting the run a round for weeks when it comes to an installment plan. When I call customer service I have been told three times that it is processing and will show up on my account soon. That was three weeks ago. Then I called back about a week ago and the man told me he didn’t see the installment plan I need to come into the store since it wouldn’t work on my app. I told him I was suppose to have one already set up and he said he didn’t see it!!! Then I called back two days ago spoke to someone and he said he sees the installment plan on my account but it’s processing still which it shouldn’t be because it’s been three weeks or more since it was supposed to to be set up. I am very mad I keep getting the run around and different answers every time I call support. I have been a customer for years and I should be able to get this settled on the phone when I call in but every time they say processing and it never happens. I can’t afford for my services to be cut off because of all the miscommunication I need HELP ASAP!! I NEED MY INSTALLMENT PLAN PROCESSED ALL THE WAY THROUGH OR I WILL FIND A NEW PLACE TO GET MY SERVICE!!!!