UV texture image changing

I am trying to change which image is used for a UV texture over the various frames of my animation
e.g. I want to use:
picture A for frames 1 to 100
picture B for frames 101 to 120
picture C for frames 121 +
I can set a lot of other material settings though the use of the “I” insert key but can’t seem to do it for the UV texture image

I could render my animation for frames 1 to 99 - then stop it - change the image and then render the animation from frames 100 to 119 etc - but this is a bit cumbersome as in total I want at least 3 different uv textures to have 3 different images at various stages of my animation

Any ideas?

UPDATE:
I managed to cheat a bit and get the result I wanted:
what I realy wanted to do was to change a badge which was part of a human figure from blank grey to a UV image with a name on it.

I set the material be reflective and set the reflection to fade to world colour and set it to max reflectivity
I set the world colour to grey (The scene is completely enclosed so you don’t see it, also the only thing that might reflect on the badge is a plane grey wall) - as a result I got Grey
By reducing the reflectivity from max to 0 I could slide from grey to the image - which worked pretty well