Usually spoken complaints are less formal than written ones.

It's about this stereo.

I'm really not happy with this shirt.

It just broke down a few days ago.

I'm not satisfied with the service here.

Well, first the radio didn't work and then the CD stopped working.

Ways of saying something's not working or not in good condition(东西坏了或状况不好时的表达方式):

to break - glass, china, pottery
I dropped my mum's crystal vase and broke it. She was really angry with me.

to break down - a lift, a car, a machine
I was stuck between the 3rd and 4th floor for 20 minutes when the lift broke down yesterday.

to be out of order - a communal or public machine (e.g. a photo-copier, a lift)
Don't put your money in that ticket machine. It's out of order. You won't get a ticket or your money back.

to stop working - anything with batteries or that uses power
She wore her watch in the pool and then was surprised when it stopped working!

to crash - a computer
My computer's crashed. All the applications have stopped working. I'll need to phone the help-line to see if they can fix it.

to jam - a machine where something (e.g. paper) moves through it.
I want to print a card for my friend but there's something wrong with the printer. It jams if you put anything thicker than a piece of paper through it.

Asking for action (要求得到处理):

I'd like a refund please.

I'd be grateful if you would replace this stereo immediately.

I would appreciate your sending me a replacement as soon as possible.

Please let me know what you intend to do about this situation.