Silver jewelry turned black within weeks

I bought a sterling silver necklace and 5 charms. Cost a fortune. And after only one month it turned black. I have written to them repeatedly about it and they continue to ignore my emails. No response. Their product is junk and for what you pay for each charm and the necklace this stuff should not turn black! I’m deeply disappointed and regret buying from them. Will warn off all my friends and family as their products and adtersales service are shockingly bad.