How to counter black c4-push when playing the London system as white

Hi!

I am trying to learn how to play the London system as white, but have hade a lot of trouble when black plays d5 and c5 and then pushes the c5 pawn to c4. The instructional videos on the London system that I have found says to ignore the c5 pawn and develop naturally (which works well without the c4-push), but when the c4-push from black comes I cannot develop the white bishop to d3 and my whole game feels cramped. If I challenge the c4-pawn with b3 the black player just backs up the c4 pawn with b5. 

Is there any way for me to punish black in this position? If there are any instructional videos on this that I have missed I would also appreciate it!

Thanks!

open the file and place your rook on it,if you keep controll of the file and you will have a good game

After 6)..., b5 7)bxc4, bxc4 8) a4!

If he doesn't have a knight on c6 you could play a4 immediately without taking on c4, and if he defends with a6 you just win a pawn because the a6 pawn is pinned.

Also this can happen