Nikkai A70JT cd player?

hey i got bought this cd player for my birthday but the problem is it says i can preset stations into its memory, but when i do what it tells me to on the instructions it works until i take out my cd player and leave it for a while, then when i go to put it back in the preset stations have gone and i have to messed about resetting them every time. i have took it back to the shop once and they thought it was a fault but this new one is doing it too! does any body no how i can save the stations so they stay in its memory even when i take out the cd player for a while ?