Defective replacement modem

I had purchased my G34 modem five months ago and it died without reason; obviously still well within warranty.  Waited 14 days to get a ‘new’ one ( I was told it would be a new one) only to find out that it is a refurbished one and now it is disconnecting every day at random times without reason and for long enough to interrupt my critical work!  As I was waiting (for far too long) to get this refurbished replacement (that also DOES NOT come up as a S/N that is recognized for warranty assistance now), I hooked up an old modem just to be able to do my job and had ZERO issues with the modem!  Now I cannot get technical support because this refurbished model is not recognized by the system when I enter the information sent in the box!  This is ridiculous- I need a NEW modem to replace the defective original one and now this refurbished one that is not working.  I am seriously upset at this product, and the lack of access to customer support for warranty issues.  Spending $200 for a modem should guarantee a certain level of quality!