All Medigap policies are standard (assuming that you are not dealing with Medicare Advantage policies. For example, all type F policies offer the same reimbursement regardless of which company you choose – even though the premiums for the same policy may differ. In my opinion, the best policy is type F which reimburses you for the co-payment for all doctor and hospital visits as well as the Medicare deductibles. The premium is about $150-$200 per month depending on age and location of residence. My experience is that Blue Shield offers this policy at the lowest cost and also give you a discount by enrolling for auto-pay or if your spouse is also covered.
I don’t understand how you are not receiving payments unless 1) the Medigap plan requires co-payments for doctor’s visits, or 2) Medicare has denied reimbursement for the doctor’s expense, or 3) you are in Medicare Advantage and go out of network.
My advice would be to ditch a Medicare Advantage policy if that is what you have. Then buy the best Type Medigap policy (F) and pick the insurance company with the lowest premium. Unfortunately the period for changing policies just ended foe 2018. Also, there is a disclaimer that insurance companies are not required to accept you if you are changing to a better Medigap policy.