If you can't talk anyone into wanting to do it, there aren't really many options other than demo and repour. A lot of people attempt to add material on top to smooth the transition, but that just adds weight to the slab, which will encourage it to settle further. The cause of the concrete settlement is voids under the deck, so unless something is squirted under the deck (concrete leveling process) or the deck is torn out and replaced, there's no way to access the voids.
Some DIY people attempt to dig down around the outside edge and pack sand or dirt under the deck; this often results in the deck settling further, because the outside edge of the deck is often the only things sitting on semi-solid ground. We recently pumped 11 cubic yards of grout around a pool after the owner attempted to excavate all the way down to the pool floor and build back up with 6x6 and 4x4 pressure treated lumber (see photo). He spent 3 months working a couple of days a week, a ton of money on stone and lumber, destroyed 4 of his skimmers, and after assembling the entire apparatus, was still unable to lift the deck all the way back up with bottle jacks, which was his goal when he started. Even in the areas where he attempted to pack sand under the slab he had 6 inch voids for the first foot out from the pool wall.
I would attempt to find another contractor who may be willing to lift it. Whatever you do, don't let anyone tell you that adding material to the top is a long term solution, and before embarking on a DIY, make sure that you account for the cost of your time for what will invariably be a very long and arduous task.
Some DIY people attempt to dig down around the outside edge and pack sand or dirt under the deck; this often results in the deck settling further, because the outside edge of the deck is often the only things sitting on semi-solid ground. We recently pumped 11 cubic yards of grout around a pool after the owner attempted to excavate all the way down to the pool floor and build back up with 6x6 and 4x4 pressure treated lumber (see photo). He spent 3 months working a couple of days a week, a ton of money on stone and lumber, destroyed 4 of his skimmers, and after assembling the entire apparatus, was still unable to lift the deck all the way back up with bottle jacks, which was his goal when he started. Even in the areas where he attempted to pack sand under the slab he had 6 inch voids for the first foot out from the pool wall.
I would attempt to find another contractor who may be willing to lift it. Whatever you do, don't let anyone tell you that adding material to the top is a long term solution, and before embarking on a DIY, make sure that you account for the cost of your time for what will invariably be a very long and arduous task.
