on demand/room to room not working

hello,

new to this. I just had dtv installed 2 weeks ago i had to have them back to my house 5 times as system did not work and still does not work. The problem seems when the dtv is hooked into the wireless router via a box they installed my room to room and my laptop stop working. Last tech out here said it was prob because dtv box and computer were on same channel and interfering with one another so he told me to unplug dtv from router and plug it in when i want to use dtv on demand. When dtv is unplugged my computer works and the room to room works. when dtv is conected to router all work for a wile then internet and room to  room go down. tech said that maybe buying a new router would fix problem but i do not want to spend money if this isn't a sure fix. I am not a very tehnical person so any help i can get would be appreciated. thank you

heather