I need help cancelling service and stop billing me

I moved out of an apartment and cancelled my cable and internet service effective 5/31/2025.  I returned my equipment to a retail store on 5/31/2025.  I am paid up on my bill through June 2, 2025.  I then received a bill for June 2025 services which makes no sense since my service was cancelled effective 5/31/2025.  I have had multiple chat sessions and several phone calls about this with Comcast and I get a different story every time.  As it now, Comcast tells me that I have to pay the June services bill and then wait for a refund,  This makes no sense,  I should receive a small credit since I cancelled service prior to the end of a payment cycle.  PLEASE PLEASE SOMEONE HELP ME.  I am an older disabled person and this is causing my undue stress and aggravation.  Trying to call Comcast and re-explaining my situation every time is at least a one hour commitment and the request I made go completely ignored.