change rate plan

More details on the rate plan involved and the rate plan you were trying to change to might be helpful?

Plans have names...

Unlimited starter, unlimited extra, unlimited Elite, unlimited premium... ?????

These are phone plans.   Is the device a phone?

It is possible that there might be a technical issue or a limitation with the system.

Hello @Maisiebooth, thanks for posting on the Community Forums. We can definitely work together on your concern with accidentally changing your rate plan.

We know that this is something very important to you, we'll be happy to help you. 

Let's meet in the Direct Messages to get started. (Look for the chat icon next to the bell icon in the upper right corner of the page) and, check for the notification.

Scarlett, AT&T Community Specialist.

@ATTHelp 

Scarlett, how about you help the OP who has the problem?  Not those who commented who aren't having one?

My current plan was AT&T 1Gb with 2 phone lines. I was trying to upgrade to the unlimited plan for just une phone line, but the system prompted the option only to change for the 2 phone lines, not one as I was intended.

Okay this is confusing already. You indicate you have three phone lines, are all three phone lines currently on the same post paid plan?

Yes?   

If you are on an old 1 gig plan, you can't change on your own.  I believe that plan is more than 10 years old. Call att.  

In order to change one line you would have to separate it from your current plan it would be on a single plan, on your bill.  

You would wind up with a group one and a group two on your bill

The unlimited line would be listed as a single line plan at the prices that are listed online, 85, 75, 65