How about this, if you didn't have FERS you would have Social Security. SS plus TSP would cost the government less than FERS plus TSP (and be just like the private sector so nobody would complain)
Some agencies, e.g. USPS, make that payment out of revenues received in payment of postage ~ not from spending your tax dollars. The poor schlubs who just want to advertise their wares to you, or sell you cruises, or maybe news about what your TEA Party chapter is up to 'locally', pay that.
Regarding COLA you have to remember the people getting the retirement didn't create the inflation behind it. if you can ever get to a zero inflation situation (like we've had for the last three years), then COLA turns to ZERO, just like with Social Security.
BTW, you forced the government folks into Social Security already ~ which is another thing I'm curious about ~ your Democrat masters told you that it would be good for Social Security to include the federal employees in the system ~ that there'd be a "profit" to the system ~ so, where's the profit? Did the Democrats lie to you again?
You should take appropriate action and get the pick-up trucks out and go after those dasterdly people.