You can get a tech to replace it for you,or you can try and do it yourself. However it may not be that cheap.
First I would make sure you are actually using the right kind of SD card. If it she wrong size (not physical, but storage size) for the device (they do have limits) then that could be your issue.
You can also look into the slot and make sure there is nothing in it (dirt, debris, etc.) or nothing bent in it.