koodo tab balance

So I purchased my phone 2 years ago in July started paying my bill July 16th of 2020. I was on a 24 month tab charge of $33. When i payed my phone bill ast month, June, my tab balance displayed $0. I now have my bill for the month of july and the tab charge is still there, even though last month after i paid it, it told me $0 tab balance. If i do the math correctly june is the 24th month that i payed for my tab balance. So now im paying technically 25 months and it makes no sense to me. I contacted the support through phone as well as went into an actual koodo place to try and solve my problem and all I kept getting told was July is my past payment. Okay, but why am I paying 25 months on a 24 month plan? I'm so confused someone please clarify