My Disappointment with Oral-B Mouth Shower Machine

I bought an Oral-B mouth shower machine for ₺2,400. So, on Hepsiburada.com, they were offering a deal where you could try out the product for 30 days and get your money back if you weren't happy with it. But when I got and tested the product, it didn't meet my expectations. When I tried to give it back, they said they couldn't take it because it's a personal hygiene product. I feel like Hepsiburada.com tricked me by saying they offered guaranteed returns but then didn't follow through.