(1) Suggest you contact 'white' hotel (Caravelle, etc) or your consulate for suggested priests. The US consulate is pretty good at listing this type of thing.
(2) There is the Dan Sinh Market at 336 NGUYEN CONG TRU (in the general area a few blocks south of Benh Thanh Market).
Also, if you follow CALMETTE to the intersection with BEN CHUONG (do **NOT** cross the bridge into risky Quan/District 4) but turn RIGHT and follow BEN CHUONG in a westerly direction you will find building material suppliers of all descriptions.
The VN for plumber is (according to my VN employee) "danh từ" - write it down don't try pronouncing it.
You can get all manner of construction and building materials, sinks, basins, toilets, wood, cupboards, etc.
(3) If your reluctant fridge has a name - look for a dealer in telephone book Yellow Pages) (free from an office at the back of the main post office) (and on-line) or ask around at Danh Sinh.
This market is big - has many entrances on different streets. One area has army 'surplus' whilst other areas have new products in modern stores. Look for a refridgerator shop.
A word about these areas. Do NOT be concerned about your personal safety; you will be stared at as not many Foreigners are into the construction business. I visit often and have never been ripped off and they even offer sage advice.
A fallback position is to seek help from the maintenance people at a 'white' hotel as they keep the standards to that expected by Foreign visitors.
If you know any D-I-Y you might be better off getting the parts and doing it yourself.
Need more help you can contact me at < site@virtuallythere.ca >