Reliance Digital / Philips Headset — Poor quality and then refusal or replacement

I purchased One Philips head phones worth 400RS on Sunday 29th March, and I did not notice that seal of the case was broken and case was stapled, as we trust that large retails like reliance keep their quality high. Now when I tried them for the first time, I saw quality of that was really poor. I went next day to get a changed head set and they simply refused to do so, and there explanation was that we have brought it sealed open.
I do not understand how we can check quality of something without looking/using it – as they don’t even keep trial sets to check, and the quality of headphone is so poor, it makes me feel like the same as you can get from Streets.
If two big brands like Reliance and Philips will treat customers this way then I would like you to step in and please try to investigate, all I seek is they should replace something which is not upto standred and they have charged for it.