I try and keep it simple..if you have wifi check that you have a password if it open to anyone people are going to leach your bandwidth. if you have comcast or another cable company look at the cable modem...the newer modems do cable modem standard rev 3.0 (channel bonding) think of it as taking two two lane highways and making them into one large four lane one.
older 2.0 modems cant. just google the model of your modem it tell you if it 2.0 or 3.0. if it rented have them swap it out ifyour paying for more speed then your getting. run a mlaware byte and an anti virus sweep. ether of those can suck up bandwith.
do a few online speed tests. durning the day and at night. do a print scree n or save then showing the tech and isp your not getting what you paid for. with cable and dsl modems the speed you get depends on how strong the signal is ans how bad or good your line noise is. with dsl the further from the home office the slower your speed is. one other thing with wifi it depends on the age of your wifi router and your card/usb stick. the older b/g cards are a lot slower then the n cards. check the mode number of the router and your card or connect speed. if your using a b/g card your speeds are going to be fixed slow.