Bummer :(

They should have picked up on this angle when they templated. However, you may be able to fix this, place a piece of wood in the toilet opening from the top corner of the pony wall to the door way, use some shims and you may be able to push(force) the pony wall enough to close up the gap. Fasten through the cabinet into the pony wall to fix it in place.

Graham

Cover top of pony wall with a piece of 1 inch wood...wide enough to cover granite space and paint white like your woodwork.

either cap it with something or have a dry wall guy come out, sheer off the top and redo it so it's straight. Not that big of a deal. Any stone left over from the vanity? you can cap it with that and have a teeny overhang on both sides.

Thanks for the suggestions so far! I did think about doing a white shaker look on the pony wall and getting a filler panel in the same espresso color that my cabinets are in for the cap, but I'm not sure that would work.

I'm w/ Kitchen Abode & Beth H. on this. This is fabricator's problem due to improper templating. But pony walls are not immoveable objects. W/ relatively little pain & cost you should be able to remove drywall & re-do square to granite, then cap w/ granite or wood. The correct sol'n would be to have fabricator replace, but given ease of working w/ pony wall & drywall that would be like using a sledgehammer to drive a thumbtack. But he should be willing to pay for pony wall as it will be faster & less expensive to him.

Sophie's advice and after you're through but before you put the cap on, run a healthy bead of latex caulk into the gap between the stone and wall. Shove a stick between the toilet wall and the pony wall, pushing the gap shut and leave it there for a day. Might need to set a piece of plywood over the drywall at the floor plate and give it a whack or two with a sledge hammer.

Vote for Sophie's solution. It will correct your gap problem and your pony wall is too short.