Recurring landline problem

How do I get a repair issue escalated? There is a problem with the underground phone line in my area that sometimes causes my landline to go out when we have a heavy rain. I have been dealing with this issue for several years, repeatedly. I have requested that my issue be escalated with several people I spoke with. I have asked repeatedly to speak with a supervisor, with no success. Each time it happens I submit a repair request, a technician comes out and "repairs" the problem. I finally had a technician admit that the problem was not something that he could actually fix because it would require the problem being located and the line dug up and replaced. All the technicians can do is slap a band-aid on it until next time. This is the 3rd outage in the past 6 weeks. I have very poor cell service and I need my landline for my my 83-year old mother. Sorry for the long post, but if anyone has some advice on how to handle this, I would be very grateful.