Overcharging

So, my phone was back on in Jan .Had a little financial difficulty however I paid full balance on Jan 7th.so, balance was 0. Come Feb 2nd new bill is generated and it shows Jan -feb plan charge 57.10 (prorated bc Jan 7th-feb 2nd) yet..it also had "Next Month Feb-March 65.00?;; I contacted them online and the chat rep stated since the phone was disconnected the following bill will have the next months amount on there as well,..ummm..news to me. ..In return I asked  if that is the case will I have a bill on March 2nd for 65.00..due March 25? And she states "yes and no."   You will be billed however the last month of your service will be credited for that amount. ". Heck no. I am not falling for that one. I told her Sprint told me this when I finally figured out the 1st month I got this phone in 2018 they got an extra month out of me. She then continued to transfer me to someone higher up. The next rep clearly understood what I was catching and had no explanation for it. She said someone would call me in 24-48 hours to fix this. This was Feb 19th. Since then I have contacted them 3 times and all day the same thing ...we will fix it.  Still no fixing has been done . Then they expect me to pay almost full price for "an upgrade". . I am very very tired of having to fix my bills each month and speaking to the online chat reps is a headache in itself. Very rarely do I get an honest person. Idk,maybe I'm hoping someone sees this msg and decides to help.