Audi 2014 TFSI the coolant warning comes on I have filled the reservoir but it does not seem to fill the whole bottle, the coolant I do put in only lasts maybe 500km. what could the problem be?

SOURCE: Coolant fill procedure

NEVER open the radiator when the car (or any other engine) is running!! The radiator is part of the pressurized cooling system (under that cap is coolant at 15psi)

Correct way to check the coolant in the radiator, is wait until the engine is COLD, then remove the radiator cap and re-fill.

SOURCE: Coolant filling up overflow bottle

You may need to ask AAA to put a radiator pressure tester on the resevoir bottle and pump it up to operating pressure(Pressure cap rating) and see if it over pressurises while it is running at operating temp,rev engine up and down and watch what the testers pressure readings do,it should move up and down in sync with the water pump.If the pressure keeps building i would have to believe that combustion chamber gases are over pressurising your cooling system.Also test the pressure cap is functioning within factory specs.

SOURCE: Coolant warning lights keeps coming on

Audi TT's only take G12 coolant (vw/audi propriatary formula) you can add some distilled water to the water level to prevent the light from coming on, but as you explained you keep adding fluid (of some kind) and the warning like returns. that's a little evident that you have a leak somewhere.

put some paper towels or something under your car when you park it for the evening. when you come out the next day, pull the car away from the spot and look at the paper towels. if they have orange drops, that's your G12 coolant leaking. like McMuff460 said, check all the clamps/hoses for signs of the leak. if you don't find anything i reccomend taking it to a shop for them to check out. Your water pump might be on it's way out.

Don't ever put any other fluid other than G12 coolant and distilled water into your car's coolant system. It will cause some major issues with seals, leaks, and cooling performance.

SOURCE: radiator coolant or reservoir tank always full

Relax, there is no problem.

When the water / coolant gets hot (inside of radiator/engine) it starts to boil, ofcourse when it boils, it expands, so the fluid in the radiator has to go somewhere, thats why there is the overflow reservoir. So, when the fluid boils, some moves to the reservoir to avoid any potential problems with the radiator, such as it blowing up, or not being able to cool off all of the fluid running through the engine.

But relax, its normal.

SOURCE: Coolant warning light came on. Where do I put in

It'll be a semi transparent plastic container with either green or orange coolant in it. should be on the right hand side by the firewall I believe. Make sure the engine has been off for at least an hour and place a towel over the cap before opening. Open the cap slowly as there may be pressure built up and you don't want it to spray... Also do not mix green coolant with orange coolant...