Will I be charged extra for not returning return slip?

[skyliner34]

Okay some guy on the tech said I could return the wireless N router that I paid 79.99 and he said he would ship a return slip now at that time I didn't know I couldn't return so I called back verizon to find out if I could return and than the 2nd guy said that you won't get back money. Now the 1st guy is shipping a return slip but I won't receive my money back for my router so I am not going to ship it back so what will happen if I don't return that slip?