How to use 2 len conn...........

Hello,
i have 750ul plan from bsnal and my bandwidth is 256 kbps and modem is zte zxdsl 831all , i have two len connection on a single line 1st 100 mbps from len cab.. and 2nd is 10mbpsby usb, i can use only one len conne.. at a time to brodband conne.. can i use both conne.. at same time to more bandwidth . bridgeing is not make any effect ..