ACT Fibernet — Act Fibre net charging money even after disconnection of internet

After my pre-paid plan of 6 months get over, i disconnected my internet through their app i disconnected my account of act fibre net and discontinued my service and received message from the company of deactivation of service but im still receiving messages from Act Fibre of Rs 3886.92 and again added due Rs 272.45 for April month.

i didn't use their service after my plan ended, but still, they are charging me for their plans pls look into the matter as this is mental harassment.