Refrigerators, air conditioners, ice makers and aquarium chillers are all the same basic thing. If someone is qualified to fix one, I see no reason they couldn't fix them all.
I think that if you search for a specialist, you'll pay for an aquarium chiller specialist (we get beat up in this hobby all the time).
It'll be cheaper if you take it to them, but it would be awful convenient to leave it in place and have someone make a house call......