new ipad pro will not hold charge How do I know the power of my charger if its 12W or 29W?

iPad 12.9 pro 64 Gig ios 11.1.1

tried everything running no apps plug in with supplued charger to wall tried a new apple usb cord

get 1 ½ hrs on full charge its done this from day one.

some times while pluged in it stops charging if I notice it I fiddle around pluging and unpluging changing cords till its charging again. interesting to not looking at the battery settings it shows totaly wrong info. about what was being used and the last time pluged in I have went to verizon where I bought it. they said that normal that 2 hrs even pluged in is about right! of course I know better. what can I do? nothing they are not any help this ipad is new and I have no one to help me Apple wont help they say its working fine! I feel totaly helpless has it come to this low state dealing with companies you think you can trust??