Something you should be doing is documenting the conversations you have with customer service representatives. Some examples include calls with your health insurance company, bank, or phone provider. Start an excel sheet and be sure to write down the company you're dealing with, date and time of the call, name and the ID number of the representative you spoke to, and the outcome of the call. Go a step further by asking the person you spoke to for some kind of written confirmation (either by email or a letter) of the subject matter discussed.
Being prepared gives you more protection as a consumer, which is definitely recommended because the companies we're dealing with are huge corporations that can be very hard to deal with. We can't always depend on or trust the firms to document everything properly, so keep records to have undeniable proof about your claim.