Ah business ethics unfortunately your not in africa,ethics has no place in business & least of all in the african dictionary.
You know when i started with my marketing & business management studies i had so many issues.Things only turned around when i worked for free,came in first & was the last to leave & when i was done id ask if there was anything else.The most important thing to remember when volunteering is to ignore the lazy & unambitious colleagues because your gonna have to work like a dog.Trust me your gonna have to take alot of stick being the fresh fish.
Just becareful which company you choose really because its more about who your working under as to the company.Luckily for me i worked under one of the best marketing experts back home & he's ref was brilliant & actually clinched my first proper paying job.