Your options are narrower than people expect and worth knowing before it happens. Cover the gap in cash, ask the seller to reduce, split the difference, dispute the appraisal with evidence through your lender, take the file to a different lender who will order a fresh appraisal, or withdraw under the financing condition if it is still in place. Each of those costs either money or days.
A dispute has to be built on facts, not opinion. Appraisers working to Appraisal Institute of Canada standards document their comparable sales and adjustments, so the productive route is showing that a comparable was misapplied, that a recorded floor area is wrong, or that a finished basement was never counted. Sending photographs and permits through the mortgage broker is the normal channel.
The wider context helps you judge whether the number is plausible. The Saskatchewan REALTORS Association benchmark is $444,700, up 2.8 percent year over year, and appraisals lag a rising market because they read closed sales. Joel Dyck reviews the comparables in a low report line by line before a buyer accepts the conclusion and reaches for cash.