Congratulations! It's unlikely you are losing out, unless you think medical insurance is a waste of money - as there is a financial cost to you where the employer pays your medical insurance premiums.
You are liable for benefit in kind tax (USC, PAYE, PRSI) on the premium amount. This works out as far less than you would have to pay if you bought the same policies personally on the open market. Based on your info above, it looks like you are getting €2800 worth of premiums for €877?
You are entitled to a refund of 20% as a tax credit for the value of the policy. You have to claim this yourself from the revenue usually, either by completing an IT5 form or phoning them directly. To claim the refund, you need to know the gross annual premium of your policy \ policies.
Most of the time the premium is shown as the net amount, so be careful.
Here is where it gets messy. The tax credit is capped as a max of 20% of €1000 (so for me, my tax credit was €200 even though my premium was €1400). I don't know the ins and outs of claiming on a family policy e.g. whether you are entitled to 20% back on each of the 4 premiums (at a guess, adult at €1000e each, and kids at €400 each, for example), or just a single 20% back on 1 premium.