MTN worst service carelessness

On the 6/11/2023 I went to Mtn shop in West Street Durban to pay for my router the lady that assisted me asked for my phone number I gave her and paid R249.00. On the 11/112023 my router was disconnected because they said I didn't pay for November, I called MTN and the consultant told me that I paid for the phone not the router, that phone they credited I finished paying for it years ago. I went to Mtn shop again and they told me to phone the call center, why because they did the mistake. Until today that query is not resolved. Today I went again to pay for the router why must I pay twice for the Month of November?