Time to look for a new phone again

Fairwinds

I am nearing the end of my 4th cashback deal with Mobileshop and have received all my cashbacks to date, admitedly having to chase them a bit more these days. i would normally take out another one, but my problem is that I don't want to go with O2 or Vodafone as I cannot get a signal at our house with either of these two. I get loads of free minutes that go to waste as i can't make (or receive a call from the house)

T mobile however gets a good signal so would like to go with them if at all possible.

So to my question, who is the best cashback provider for T mobile deals.?

I don't mind having to chase the cashback as long as it comes.

Who should be avoided.

Thanks a lot