Replaced waterpump,thermostat,heat sensor ,still over heats

is the cooling fan working correctly, is gauge reading correctly. I know you said you replaced heat sensor but gauge still could be giving wrong reading.

Try this How to Stop an Engine from Overheating

Could be that fan is not kicking on. check and make sure it is connected. could also be a vapor lock. some cars require bleeding water system and if so most bleeding screws are located around thermostat housing. Call local autozone and ask if your car requires bleeding water system....NOW the overheating could be from fan not kicking on and the best way to find out is to turn on defrost and if fan is working it will kick on automaticaly. If it does kick on then this shows that fan is working fine but this does not mean that fan is running properly.The fan is controlled by a heat sensor which kicks the fan on when motor reaches a curtain heat range. If this sensor is not working it will cause car to overheat.... Could be also that waterpump is bad.Not all waterpumps leak when they go bad.Sometimes the impeler on the waterpump which is what moves water through the system simply stops working and this would cuase it to overheat.......hope this info helps and good luck...Please rate my post and if you need more info fill free to contact me...Need to find where leak is coming from also for this is more than likely the problem........

Did you bleed the coolant lines to let all of the air out? If there's air in the lines, you will have the issues you're describing.

sounds like electric door motor is bad in front of the heater core. door is'nt opening

A lot of the time the core in the radiator are partly pluged. The radiator needs boiled out or replace the radiator. One other item that can cause problems is old hoses. The bottom hose could be collapasing under pressure and the radiator cap could be at the wrong pressure setting.

Well, is the cooling fan working as it should? It should kick in at about 190F, if it doesn't the engine temp sensor may be faulty. You should also check the radiator, it can be clogged inside and outside. You can clean it up by disconnecting both hoses and running your garden hose through it until water comes out clear. Remember to replace all fluid with proper VW coolant.
Also clean the outside of the radiator as tree leaves, dirt and bug on the outside reduce performance greatly, clean it with a brush and a low pressure garden hose until you can see through it.

waterpump may not be circulating correctly

Only 2 parts remaining are the thermostat and waterpump. Always start with the thermostat when diagnosing an overheating problem. If the car is overheating constantly under all conditions and coolant is backing up into the reservoir, it's very likely to be the thermostat. If it only overheats at low speed or idling, it's more likely the waterpump.

the system requires venting several times after replacing parts, there is a vent port on the 3.5l at the thermostat housing, crack it open to vent air out after running,