Images cut out of models wearing clothes and put on a white background

My business sells clothing online via an Amazon Prime seller account. We must list products with a white background and in 2000 x 2000 pixel format due to Amazon's requirements, however our suppliers supply us with photos of the clothes being modelled on a grey or off-white background. There are around 300-400 images which the backgrounds need changing for by 17 March 2019. Please contact me if you are able to do this.