If you have been pretty satisfied with Vodafone service otherwise in those 11 years, i think you should try adopting a different strategy for that weaker signal...
Contact Vodafone, lodge a complaint, request a booster in your premise. You may have to contact higher ups like Nodal, Directly to Senior Level for this thing to materialise in case Customer Care ignores. Many people in the past have been successful in getting Vodafone boosters in their office if majority of the office area was with less/broken coverage. You being a Doctor & customer of 11 years have a strong case. Give it a Try.
Secondly for Tariffs, If your signal problem do get sorted out, then put in a port out request, negotiate strongly with Retention, Keep all the proof of your interaction (Voda of late has been notorious for promising something & not giving lateron) and get a better plan. Again people have got very good retention plans from Vodafone. See This Topic MNP Retention Offer You Received.
What i am trying to say is that with this Telco behemoths of today, play strategically first (above steps) and if that fails, then only emotionally (showing them the boot). May yield better results.