t mobile bill keeps increasing for no reason

I've had internet services threw T-Mobile for years well my girls need their first phones and they were getting older so I got them each one When I got my phone service threw T-Mobile I was told my bill for 3 phones and Wi-Fi would be 190 basically I got 2 phones and one free line then first bill came 380! Well they say it's for the first time bill okay whatever paid that then ever since then each month my payment has been over 300 every month I'm having to call a supervisor to fix my plan and it seems to be pushed more and more for my payments for late fees reactivated service etc. I shouldn't have to pay no more than what I was told to pay I agreed for the 5 Th time to pay 240 and her I am waking up and my phone has been suspended due to nonpayment? After I just paid 240! I'm having to make a payment play arrangement to even get my phone back on I don't have the time to always call and worry about a phone bill I've already paid I'm a single mom of 3 girls I can't keep doing this well I bought my girls iPhone threw T-Mobile now I'm stuck with them till I pay off their phones it's ridiculous corporate needs to address these issues before they start losing more customers! I've loved this company I thought I'd be okay with my cell phone service threw them but each month with no changes to my account I keep getting a higher bill each month my bill now says I owe 551.83!!!! Like what! Very disappointed T-Mobile