Re Elixir strings. The first set I bought lasted well over a year. The second set (bought off eBay) lasted a few weeks. I don' t know if they were cheap copies or just a rogue set of real Elixirs. I wrote to Elixir and they kindly sent me a new set of strings.
I should add all subsequent set of Elixirs have not had the longevity of my first set. Don't know why.