TMobile Home Internet -- Great signal but no internet?

I am having a similar issue. when I first started with T-Mobile home internet, I was living in a small studio apartment  in the country. The signal and internet was great. Never had a problem. Well about 5 months ago I moved about 50 to 100 yards into a little bit bigger place and my internet went to. My modem is reading "GOOD SIGNAL" and but the connection sucks. I can't hardly do anything online and here I am trying to plan a wedding but can't hardly do when I need to do online with my computer. But when the signal on the box reads "WEAK", the internet runs like a charm.  now you would think that when you have a good signal the internet speed would be great, but no it's the opposite and it's very frustrating. And I have called them 3 different times on the issue and all they want to do is reset the box back to factory which only helps for about the first 30 minutes if that and then I am back to where I started. And they have made no effort to exchange my box for a new one which I have suggested every time I call them. If I have to call a fourth time I am gonna get rude with them cause I am having to pay for this expensive and I can hardly get on it at times. I just called them earlier tonight… that was the third time for this particular issue. I called them last night to turn my cell phone off cause the signal on it sucks and overly priced plans. so I went back to my with my previous carrier and they tell me that it will be turned off at the end of the month. Why couldn't they do as I requested and turn it off when I called ? But no they wanna wait til it's accumulates another bill.