Stay away from Rain, their sevices only work certain times of the day

For last 3-4 weeks I have been experincing slow connections every day, especially after 6pm. Everytime this happens Rain asks me to move the router around and do speed tests then they fix the problem for a week or two. My router has been stationed at the same place facing the tower since I have had Rain, I do not understand how you can get 60meg in the mornings and only 4meg in the evenings, This has nothing to do with where the router stands.