Tata photon connection very slow and want to change plan or connection they don’t have customer care picking calls

Location/place: Bangalore

I have my account number 906428011 and I am under the 5GB @950 plan and would like to change the plan or disconnect. The call gets disconnected when I call 1800266121 which is their official customer care. When I call the other customer care numbers they ask to call on this number. I have been trying to put my complaint through for 1 month but in vain.