Hang on to it, I have an assortment of meditation paraphenalia that I have purchased over the years and some things that I found useless shortly after purchasing them, I am using at the moment. You could also donate it to a dhamma brother or sister when the time is right. Keep on keepin on, and you will be successful.
Also, feeling comfortable and relaxed is not always the way the present moment shapes up. Its nice to start sitting in a comfortable and relaxed posture but after some time(maybe only 5 mins.) this is bound to change, our job is to simply observe this process and not add additional mental suffering. If you can sit relatively comfortably on the cushion or on the bench to start then stick with one of these, but it is normal for discomfort to rear its ugly head at some point. Concentrate on the breath or whatever your object of meditation is and when discomfort seizes your awareness bring it back to the object. If this is not possible and the awareness is drawn towards some pain or other intense sensation then make this your new meditation object. Look at the pain, does it move around, what does it feel like, how long can you sit with it before you change your posture, does it eventually subside, if you make subtle adjustment to your posture does it subside or get worse, does it appear quickly or slowly build. Don't think you are not meditating if you focus your awareness on pain, if you can observe this pain and gradually build equanimity towards it, you are well on your way.
And, I was not joking when I said you are lucky to have this pain. Pain is one of the greatest teachers you can have, very quick progress can be made observing pain. Just remember to be kind to yourself during this process, and don't blow out a knee!!
If you find that this pain arises after 10 mins and you usually change posture, then see if you can make it another 3 mins before you adjust posture, sit with the pain and look at it, really zero in on it, with the full intention that I will adjust my posture when I reach my limit. In my experience this time will increase and you will find that the pain does not just keep on intensifying endlessly, it subsides and then intensifies and then subsides and then intensifies. Believe me I know when it intensifies it can feel very solid and permanent, but this is not the truth. Focussing on pain will really concentrate and sharpen the mind.
The way of the cross, purification through pain
It's a rocky path buddy!