Problem with memory module

Hi there

Less than month ago I bought Dell Inspiron N7110 with i7 core. After three weeks of using it problem with memory module apeared. After turning on there was four consecutive beeps repeating. So I took it to the dealer where I bought it and they deduce that there is problem with memory module.

Question is, how come that in Serbia they are selling such laptop as Dell Inspiron N7110 with  memory module so cheep that goes out after only 3 weeks of working under normal condition?

Problem wouldn't be so big but in service they claim that they need more than 10 days to replace memory module? How come?