I'm afraid that there isn't a single word meaning our company as opposed to another company in English. If it's too confusing to use just plain company, then you may have to come up with some form of us, this company, our company, etc. on the one hand, and affiliate or associate companies (or client, if that's applicable) for the companies "our company" is working with.
Piece of junk refers to something that is cheap, shoddy, or worthless. It can be used as an oject as in "This piece of junk won't boot." or a modiying adjective as in "This piece-of-junk computer won't boot" (with or without hyphens).
Related adjectives can be used with the name of the device. These include:
"Junky", "shoddy", "trashy", "lousy", "worthless", "crappy" (oh, and, of course, "shitty").
Boat Anchor which merely means the device is only suitable for that purpose. "This computer has become a boat anchor" (Urban Dictionary, definitions 2 and 3, Ham.net shows the term used in practice.)
Doorstop similar to "boat anchor". "This computer only works as a door stop now."
Junk Box No longer suitable for anything except to be cannibalized for spare parts. (See wikipedia.) Usually this refers to just the parts themselves, already disassembled and collected into a box. But it parallels your German reference, so I thought it was worth adding.
We also refer to some things as "hangar queens", which is alludes to aircraft that spend more time in repair than they do in service. Any products that can't get through the production process may be relegated to being hangar queens, with hopes that someone will eventually figure out how to repair them.
Best Answer
"Second hand" goods are goods that have been previously owned. In the USA, "used" is more frequently used.
If the goods are old enough and in good enough condition, they may be considered "antiques".
When these are sold in shops:
There are also "antique shops" and "antique salesmen", if the goods are actually antique (although sometimes the definition is pushed somewhat).
In recent years, particularly for good quality second hand clothes of some age, the word "vintage" has come into use. "Vintage clothes shop", or just "vintage shop".
In the UK at least (and, to my knowledge, everywhere else) "second hand dealer" is not generally used when the goods are to be recycled (as opposed to re-used whole).
So, I would use "second hand dealer" to describe someone who buys and sells used electronic equipment.
I would not use "second hand dealer" to describe someone who buys and sells newspapers for recycling. Perhaps a "recyclable waste dealer", if they are selling on to whoever does the actual recycling.