Data doesn't work unless I have 4 bars, and is very slow. [ Edited ]

[naphthalene]

When I first got my Infuse 4g I could get 6Mbps down and 3 up easily. Then I converted to a 2GB plan and either at the same time or a few months later (I couldn't tell if it was immediate or gradual...) and now my data plan is essentially useless. When I had the 200MB plan (and like I said possibly for part of the 2GB plan) I could get full speed with one bar and wouldn't have a problem connecting calls. Then soon after I got the 2GB plan I noticed that data didn't work at all unless I had at least 4 bars. Sometimes even then it wouldn't work. I did a speed test and I only get 100Kbps. 1/60th of what the speed should be... my phone clearly shows that there is HSPA+ everywhere I go to on a normal day, and the AT&T data map confirms it. Not only this, but my calls can take up to a minute to start ringing unless I have 3 bars or more, and usually don't connect if I have fewer.

So I tried factorry resetting my phone which took a while and was annoying to have to set back up. It still does the same thing.

What's wrong? What do I do? Why did this happen?

Oh and as a note: on the Infuse 4g it has 5 bars, I know some phones have different amounts, maybe up to 6...

[jamileh]

Your choice of data plan has no bearing on the speed of access so I'd definitely look to more troubleshooting options. 

Perhaps there's an issue with your SIM card. Are you able to get to a retail store to do a little SIM card troubleshooting?

[naphthalene]

Is there any reason a SIM card that's been in my phone since I got it would suddenly stop being 100% functional?

[jamileh]

Without troubleshooting, I'm afraid that's a question I can't answer. 

There might not be anything wrong with the SIM at all, but it is a valuable troubleshooting step. 

[naphthalene]

OK I'll try going to the AT&T kiosk in the local mall (only AT&T store for miles) but my guess is they're going to try to sell me something or say how I'm being throttled somehow on a tiered plan.