bad savings account management

I actually cancelled my membership early December 2014, all accounts were up to date, I had a little left on my savings account. Afterwards they paid claims end December (listed only in January 2015, when I was not a member) exceeding my savings account with notifying me. They won't admit that it is their mistake for exceeding my savings account, keep on sending me bills without information for settling the bill since I am not a member anymore. Now suddenly I own another months worth of savings account, without new claims. I am tired of phoning since I am always on hold for at least 10 minutes.