hello my superb tdi v6 automatic is going gpto 3rd gear only  what type of problem can be 

If it is going to 3rd only I think the gearbox is in "limp mode" so there will probably be a fault logged.  Get it hooked up to someone with VCDS diagnostics - they're really complicated beasts.

 

A simple thing for you to check would be under the front carpet on the right hand side of the car - that is where the ECU for the gearbox is (TCM - transmission control module).  If you have water in the car (see the big thread about it) then it can stop the TCM working, which can I believe leave the gearbox in a limp mode.  If the TCM is wet it may well not even respond to VCDS diagnostics.

 

But, really, I think you're going to have to get it scanned.

tnx jimbof for rpy 

now i having another problem i changed my superb's gearbox but car drops pick up for some time what could be problem ?

No idea, I'm not a mechanic!  My gearbox was fixed at a gearbox specialists.  Did you scan for codes before swapping?  How about now?  You might have some clues if you get a scan using VCDS or similar of the TCM.  Perhaps your torque converter has issues.

What is your mileage out of interest?