Problem with rose plant

Early last year my wife bought 2 rose trees.
One (shown on the left in the first picture) flowered nicely, the other (on the right) didn't.

This year both flowered but the one on the left is rather poorly - losing all its leaves - and also seems to have 2 different colour roses - pink at the top and white lower down - which is strange as it was bought as a pink flowering plant.



We did spray it with a pesticide treatment but that doesn't seem to have helped.
Can anyone suggest what the problem is with the plant and how to treat it.

 

Not a rose grower myself but until someone else comes along all I can say is that they appear to be standards.
So they are budded onto stems at the height that the head tends to form.

Just wondering if the white flowers might be growing from the rootstock, whereas the pink are the variety that was budded.