I want to buy a decent sized refrigerator in Nakhon Sawan for domestic use.

Big C seem to have a reasonable range but nothing really big with a separate freezer
and auto defrost.

Are there any other specialist shops where I might find something better?

i bought mine just now at thaimart in pitsanulok. its really great, they have a huge selection. If you dont have thaimart in nakon sawan, they will drive it to you, for a fee. i got mine shipped here (phecthabun) for 800 baht. if pitsanulok is too far too drive, check out pichit, they might have thaimart.

Another option is to talk to a smaller store, they might be able to order a special model for you, if you know what you want. I talked with a store like this in petchabun, and they could bet me any model from most major brands. good prices too.

Go to the 4th floor at Ferryland; they have a HUGE selection.

Try Macro

Also, there is the second-hand shop called 24.

I bouight my fridge and washing machine and fan and micro wave oven from the new shop right next door to Big C on the mian road. Prompt delivery and very compatible price wise to anybody else. They also have a huge range of other goods eg TV home entertainment etc.
Good shopping.

if there's a macro available try them; I compared prices on the same model Panasonic fridge at tescos and a smaller appliance shop and macro were 9-10% cheaper...