My kitchen company took on a new kitchen job ( replacing…

My kitchen company took on a new kitchen job ( replacing existing old kitchen). The work include:
1. Take out all exixting cabinets, doors & counter tops and bulk drywall bulk heads to make rooms for taller upper cabinets,
2. Demolish 220 sq.ft. ceramic floor tiles and 65 sq.ft baxk splash tiles and repair the damaged dryalll
3. supply & Install new kitchen cabinets, solid maple wood doors, crown moldings, decorative fillers, window box and pelmets
4.supply & install new 12"x24" pircelain tiles on floor
5.Supply & install 11 new mini pot lights in the ceiling
6. Supply & install new 220volt power outlet for a wall oven
7. Supply & install led under cabinet lights
8. Supply & instal new brush nickel goose neck faucet with pull out
9.Supply & install Quartz counter tops
10. Supply & install new stainless steel sink
11 Supply & install new stainless steel 750cfm powerful range hood
12. Install new220v wall oven supplied by client
13.Install new 220v wall microwave oven supplied by client
14. Install 220volt drop counter top cook top
15 Supply & install 65 sq.ft3"x6" pure glass tile back splash
II have completed all abovementioned work except all the cabinet door because:
1. During the installation period this client added more & more additional work not in the original quotation,i.e. to repaint the whole kitchen; to add more decorative moldings, fillers and wood panels that are not part of the kitchen, to pick up all the new appliance for the client who did not want to pay the delivery charges; there were other work like the new appliance require 2 additional 220volt power supply and this was an expensive electrical work as usually there is only 1 220volt outlet in the kitchen, the change from typical stove to cooktop involved more countertop material and the labour for cut out and an addition of a 30" drawer cabinet to fill the void.
As I mention. I have completed the majority of this very custom kitchen in a quality and god workmanship manner. The kitchen has been up and running (the wall oven, the wall microwave unit, the dushwasher, the cooktop, the rNge hood, the fridge with water line, the faucet, the lightung) for 4 months except cabinet doors are withheld in my shop.
This is client has filed a claim in small claim court for total refund of the 2 payments ($13,000)I received as I did not finish the door work and someother bits & pieces extra work. The original quote was $14,500 plus taxes and the additional work is approx. $2,800 plus taxes.
There was no signed contract and no delay penalty clause agreed.
One more thing is that this client files the claim directly to my name not my registered Ontario Inc.
Waht can I do to fight this so unreasonable claim.
James Ng