Bharat Sanchar Nigam [BSNL] — Landline issue for last 6 years

MY LANDLINE VOICE IS NOT CLEAR AT ALL, ITS SOUNDS LIKE RAINY( voice is cracking) and can’t hear anything. I am writing this email as we ( me and my wife) both are Senior Citizens, I am 76 years and my wife is 70 years old,
We both are Medically handicapped and challenged as I have Lung/ Diabetes condition and my wife is a paralysis/Heart Patient. We are staying by ourselves and to getting help or any Medical assistance is ONLY VIA LANDLINE, We are habituate to use landline only.
Our doctor has strictly advised not to step out of home in current COVID pandemic.
We have one of our well wisher went to BSNL office along with Phone instrument to make sure it’s not the phone instrument having issue and BSNL technician confirmed phone instrument is working fine and there is no issues.
It appears there is line issue which they came couple of times to fix it but that worked only for a day or 2 and this is an ongoing issue for almost over last 5-6 years. We both are used to only using Landline and Its more of a reason to get it resolved now as due to pandemic and given our health condition "IT NEEDS TO BE RESOLVED on Urgent basis".
WE will greatly appreciate if you can look into this matter ASAP and fix it forever.